According to one biography, Robin Williams decided to test out the believability of his Mrs. Doubtfire character during filming by going as Mrs. Doubtfire into an adult bookstore and making a purchase. He was able to do so without being recognized.

During the scene when Mrs. Sellner comes to inspect Daniel's apartment and Daniel/Mrs. Doubtfire is serving her tea, the icing on his/her face is melting off. This was not intentional. The heat from the set lights melted the icing on his face and Robin Williams improvised the bulk of that scene.

Chris Columbus would use two or three cameras at a time when shooting Robin Williams' scenes, uncertain of what the famously improvisational actor would come up with. Columbus viewed shooting these scenes as if he were making a documentary.

Chris Columbus was amazed how far Robin Williams took his performance. First, he played each scene as scripted two to three times, and then was allowed to improvise, or "playing" as Williams called it. Columbus allowed Williams a lot of improvisation, because that was where the film's funniest material came from; in fact, Columbus called it magical at times.

According to director Chris Columbus, Robin Williams improvised so much that there were PG, PG-13, and R edits of the film (though always intended to be released as PG-13).

Continuity

When Mrs. Doubtfire throws the lime at Stu, it cuts to Stu getting hit in the head. When it cuts back to Mrs. Doubtfire, the same lime is clearly at the top of the fruit dish. The same lime disappears and reappears from the fruit dish several times in this scene.

As the family approach the entrance to the swimming pool enclosure, the same two bikini-clad girls cross their path twice between shots.

When Mrs. Doubtfire and Miranda are unloading a paper bag of groceries, Mrs. Doubtfire pulls out a small bag of tomatoes. In the next shot, she pulls out the same bag of vegetables and carries them to the refrigerator to place into the crisper.

When Mrs. Doubtfire goes into the kitchen, she closes a regular door in the middle of the hall. Throughout the rest of this scene, there are two swinging doors to the kitchen, and they are located at the other end of the hall.

Mr. Lundy is wearing a black suit, when he is drinking with Daniel in the restaurant. White specks appear and disappear on the suit between shots.



Factual errors

There is not a restaurant in the world that has all the cooking spices on the waiter's side of the kitchen as shown when Mrs. Doubtfire put the hot pepper on Stu's dinner. Furthermore, one of the eight line cooks working would have seen Mrs. Doubtfire season a dish that was on the pass-thru and would have either said something or remade the dish. NOTE: In a deleted scene, one of the cooks does catch Mrs. Doubtfire adding the pepper, so he/she pretends to be a high-profile Cajun chef visiting the restaurant and chides the cook for not adding the pepper.

Stu mentions that he is allergic to pepper, but his reaction is that of choking and not an allergic reaction to the pepper that Mrs. Doubtfire had put on. If Stu were really allergic to pepper, the small amount he did ingest would have had him on the floor, and he would be in great pain.

The Doubtfire makeup is a one-piece mask that Daniel can put on or take off at will. Real prosthetic make-up is composed of several pieces that are glued onto the skin, and both application and removal are lengthy processes.

In the music listings for the song Dude (Looks Like a Lady), the name of co-writer Desmond Child is misspelled (as "Desmond Childs").

There are mistakes in the restaurant scene. First the ma?tre d' ask arriving guests whether they want smoking or non-smoking seats such as Stu and the family. That question should have been cleared during the reservation call. Second, ignoring the fact that customers cannot easily enter the kitchen, there is always a head chef who checks that dishes are prepared properly - this case non-spicy Jambalaya. Third, not a single staff nor customer nearby reacts when Stu chokes.



Incorrectly regarded as goofs

During the sequence where Daniel is calling Miranda with horrible "potential nannies", Miranda is seen responding on a cell phone, home phone, and her work phone. It is entirely possible that Miranda has "Call Forwarding" from her home phone to her cell while she is out. The two numbers published may have been her home and work numbers.

When Mrs. Sellner is inspecting Daniel's apartment and he is in the kitchen, Mrs. Doubtfire's wig mysteriously changes from frayed to perfectly shaped. However, Daniel could have easily fixed its frayed position in-between shots.

When Daniel is putting in his false teeth, you can see that some lipstick got on his teeth. This is a normal problem, even on real women with real teeth. It should also be noted that Daniel was not sober at the time.

Daniel's voice-recording session at the beginning of the film is incorrect. He is recording the dialogue for a cartoon with completed animation, completed sound effects and completed music. In the production process for an animated cartoon project, the voice-recording stage must come first (with the exception of ADR, which is meant for either adding non-speaking vocal effects, such as groans and grunts that were wrongly omitted during the initial sessions, touching up lines, or replacing actors, and even if such were the case, the studio would also need to be completely silent while the actor works to ensure that the recordings are usable), so that the animators know what mouth shapes are needed for each bit of dialogue. However, according to director Chris Columbus in the DVD commentary, this was done intentionally for the film, and he had hoped that people would interpret it as Daniel dubbing a foreign cartoon. Given the 1960's Saturday Morning Cartoon style of animation, it's also possible that Daniel is simply replacing another actor who had previously voiced the roles for an old cartoon that is being reissued for reruns (this is further hinted at during his ensuing argument with the voice director, Lou, who complains that the session is already costing the studio money and time).

After Mrs. Doubtfire lights her blouse on fire over the stove, she says "first day as a woman and I'm getting hot flashes" - although it is not his first day. However, Daniel could have used it loosely and meant at a recent time.



Revealing mistakes

PIerce Brosnan's stunt double can be seen when he jumps off the diving board at the pool area.

The "Mrs. Doubtfire" face that Daniel wears is not a mask, but a prosthetic appliance, as evident by its uneven edges. These must be carefully glued down and blended with each use. It can't simply be put on and removed like a mask.

Miranda comes to pick the kids up from Daniel's an hour early. He complains and she says she doesn't have time for this as she has this errand and that errand etc to run. She could have gone and ran those errands alone during that last hour the kids were supposed to be with Daniel on his 1 day a week visitation.

Stunt double when Mrs Doubtfire's chest is on fire.

When Mrs. Doubtfire first meets with Miranda and is making tea for them, she fills the tea kettle with water and puts it on the stove, but the kettle never boils and is not seen pouring it for tea anyway, there is also no steam coming out of the cups.



Crew or equipment visible

Film crew reflected in the window of the trolley car with Mrs. Doubtfire and kids on board as it drives by.

When Daniel/Mrs. Doubtfire is in the kitchen looking in the fridge, the cameraman is reflected in the frying pan that he picks up.

When 'Stu' is talking to his friend in the bar at the pool, the reflection of the camera can be seen in the vase behind them.

A catapulting device used to force the Styrofoam head to cause Mrs. Doubtfire's mask to fall off into the alley is visible at the base of the head.

When Daniel begins to pick up and play with the dinosaurs on the table cigarette smoke blows into the shot from a crew member off camera.



Errors in geography

After the birthday party scene, Miranda accuses Daniel of bringing home the San Diego Zoo. Even though she is obviously exaggerating, the distance between San Francisco and San Diego makes no logistical sense.



Plot holes

In the pool scene, the children are dressed for winter weather and are not sweating, even though it is supposed to be a hot day.

It is unbelievable that not one of the chefs questions or has any concern about Mrs. Doubtfire entering the kitchen at will as "she" does, an area that would be off limits to anyone except for restaurant personnel.



Character error

Mrs. Doubtfire's accent is described by several characters as English, but sounds more Scottish.

Miranda, a professional decorator, recommends a "17th-century grand piano" for Stuart's B&B. The piano is an 18th-century invention, while the grand piano was not invented until the late 19th century. What did exist in the 17th century (which in fact resembled a piano) was a harpsichord.

Mrs Doubtfire's accent is not English. Yet she refers to England as an island and her home.

When Lydia is crossing the street in front of the school bus with her siblings, she checks for traffic to her right but does not look left. Instead, she is looking down at her sister.

It seems a bit rude and out of character of Mrs. Sellner to request a cup of English tea after Daniel tells her about how great of a cup his "sister" makes.