Eddie Murphy, John Ashton, and Judge Reinhold improvised most of their comic lines. Literally hundreds of takes were ruined by cast members, actors or the director laughing during shooting. During the "super-cops" monologue, Ashton is pinching his face hard and looking down in apparent frustration. He is actually laughing. Reinhold put his hand in his pocket and pinched his thigh really hard, trying to prevent himself from laughing.

Axel Foley's T-shirt is from Mumford, a real-life Detroit-area school one of the filmmakers attended. When the film came out, the school got orders for the shirts from customers all over the world.

To cast the roles of Rosewood and Taggart, the director paired up various finalists and asked them to do some improvisation to get a feel for their chemistry. He paired up Judge Reinhold and John Ashton and gave them the following direction: "You are a middle-aged couple, married for years. You are having a conversation on an average evening." Reinhold immediately picked up a nearby magazine and the two improvised the "five pounds of red meat in his bowels" bit almost exactly as it eventually appeared in the movie.

Originally two men were supposed to be working in the art gallery scenes. When the director heard Bronson Pinchot's Serge impersonation, he thought it was so hysterical that he scaled back the other part to give Pinchot more screen time. The second actor shows up briefly, with his shirt collar open too wide, and Serge comments on it.

Eddie Murphy became very tired while filming the police station sequences. The crew offered him coffee, but he refused to drink it because he refuses to take drugs of any kind. Eventually he relented and took small sips of coffee to stay awake. He became very energized and ad-libbed the "super-cops" monologue.

Continuity

When Axel is thrown through the front window of Maitland's office building he is in the sun. When the police pull up, he is in the shade. As the scene goes back and forth between the two angles, Axel goes from being in the sun to the shade, then back to the sun.

The bananas that Axel uses to disable the car are not the ones he was given.

When the goon is thrown over the buffet table at the Harrow club, his face lands in some sliced oranges. In the next shot, cream and strawberries are on his face.

When the henchmen run out after seeing the police on the monitors, their shoulder holsters disappear and reappear.

Foley and Taggart run past the windows of Maitland's mansion,which had been shot out. In later scenes, the glass is back in place.



Factual errors

Maitland's German bonds are incorrectly labeled "10,000 Mark". The official name for West German currency was "Deutsche Mark." East Germany used "Mark", but bonds did not exist there. In German the comma functions like an American or British decimal point, so the bonds were worth 10 marks.

Police drug dogs would not be fooled by cocaine shipped in coffee grounds. They would smell the drugs and the coffee at the same time. Even a few specks of powder on the outside of the crate would alert the dog.

In the pool scene, the hustler says "8 ball, corner pocket, 2 cushions." The 8 ball made contact with cushions three times before falling into the pocket. Mikey won his bet.

When Foley first enters the Detroit police station, the name on the door he goes through is misspelled "INVESTIGATON OPERATIONS DIVISION".

When Axel digs out the drugs from the coffee grounds and opens the pack,he dips his finger in and tastes it.In reality no cop would do this as they are dealing with an unknown possibly hazardous and toxic substance.



Incorrectly regarded as goofs

While Rosewood and Taggart wait on Foley to come back to the hotel, Taggart drinks coffee from Dunkin' Donuts. In 1984, Dunkin' Donuts had several dozen California locations. They were phased out in the 1990s.

In the opening chase scene, the Detroit police cars have a single beacon/siren combination. The Detroit Police Department used this design for one year before abandoning them due to poor performance.



Revealing mistakes

When Axel throws Maitland's henchman over the buffet table at The Harrow Club, it's clearly a big, burly stunt double doing the throwing.

During the opening chase, Axel is a few inches taller, with different hair and more muscular arms. He's clearly a stunt double.

At Maitland's house, after Taggart collapses on the grass after being shot at for the first time, holes in the grass indicating where the bullets will "hit" are clearly visible.

When Jenny and Axel go into the warehouse for the second time, the door is unlocked and open before Jenny even inserts the key. She never even turns the doorknob, yet the door opens.

When the cigarette truck crashes , it is apparently a stunt driver that jumps from the truck's cab.



Miscellaneous

After the shooting is done and Foley is sitting outside (after being shot in his right arm) and gets up, his gun in on his back belt. The position of the gun shows it was placed with his right hand which is supposed to be in pain such that he just shot using his left hand.

Axel books into the hotel and his bag is a specific size. When he books out and buys bathrobes for Billy and Taggart, he says that he has three bathrobes in his bag. However, his bag is no larger when he left than when he arrived. Either there were bathrobes in his luggage and the bag was not enlarged or he (being a cop) did not steal the bathrobes.

When Axel is shot by Victor in the arm the round (either .357 or .44 magnum) would have just about taken his arm off and he would have probably bled out. Yet he only has a minor wound.

Axel and Mikey are supposed to have grown up in Detroit, but, when playing billiards, both pronounce "Summers" like "SUM-mehs," which is very distinct from a Midwest accent, revealing themselves to be the New Yorkers that the two actors really are.



Audio/visual unsynchronized

When Foley walks across a tiled floor in Maitland's mansion, his sneakers make the sound of hard-soled shoes.

After Axel Foley is arrested and the police car pulls up at Beverly Hills police station, the two officers get out. As the officers walk to the rear door to get Foley out, Foley is heard saying, "Officers, if we see any like... movie stars, could y'all stop and point them out, I never seen no shit like that." One officer is heard responding "That's enough talkin', pal.". Throughout this dialogue, the officers are outside the car, while Foley is inside, the windows are up and it is obvious Foley is not talking.



Crew or equipment visible

When the police car hits the barrels during the opening chase, it's shown from the inside of the patrol car behind it. In the next exterior shot, the camera is visible in the front seat.

When the cigarette truck smashes into the taxi, crew members are visible on a nearby roof.

As Axel is led into the Beverly Hills Police Department for the first time, the camera crew is reflected in the plate-glass windows in the hallway.

In the opening truck chase, just before the shot of the green taxi, a movie camera can be seen mounted inside one of the police cars.

The tractor trailer slams into the fruit truck, which slides into a parked green Chevy Impala. Before the collision, the Chevy appears to have camera equipment under its front and rear bumpers, concealed by either black cloth or tarp. The rear camera's location becomes obvious in a slow-motion shot of the fruit truck sliding.



Plot holes

It makes no sense for the villains not to kill Foley after they kill his friend. Foley is a loose end and potential witness. They are unscrupulous career criminals and murderers. If they get caught, they are up for first degree murder anyway.

Somehow after being in prison for a few years and then working in California for months Michael is able to find Axel's apartment in Detroit. Also, the hit men from California are able to easily find the same apartment.

No reason or logic at all is provided for why Maitland kidnaps Jenny after she and Axel find the drugs in the warehouse, especially when he easily could have shot her and Axel under the guise of killing intruders and gotten away with it clean by the police.



Character error

It makes no sense for inspector Todd to consider the killers of Foley's friend to be professional hit men because they left Foley alive. Leaving a live witness and lose end around should in fact make the inspector assume the exact opposite.

In the strip club, Axel jokes that if he drinks club soda, he'll throw up, but he ordered a scotch and soda moments earlier.

Upon arresting the second robbery suspect at the strip club, Taggart puts his gun right against the suspects head. No police officer would arrest a suspect that way, for the gun's close proximity would make it possible for the suspect to knock it away.