Eastwood called Clyde the Orangutan "one of the most natural actors I ever worked with. But you had to get him on the first take because his boredom level was very limited."

Adjusted for inflation, this is the biggest hit of Clint Eastwood's career.

This is the first movie to earn $10 million or more in its opening weekend.

Clint Eastwood was advised to do this movie on the heels of Smokey and the Bandit (1977)'s runaway success at the box office.

Manis the Orangutan once got upset and grabbed Clint Eastwood while he was driving a truck. The ape's trainers were able to calm Manis down by speaking to him over the two-way radio.

Continuity

When Echo fired two rounds into the side of beef, the cigar falls out of the man's mouth twice.

The overhead shots during the slaughterhouse fight are not consistent with the eye-level camera angles.

When Clyde is riding the yellow sweeping machine there is a spoken passage in Spanish which ends in the word "monkey", then, after it crashes off the ramp and Clyde jumps off towards Clint, the exact same sentence is used again.

When Philo is in the bar at the beginning of the movie, right after the patron tells the joke about the coffee, the red headed lady's cigarette shrinks about 3 inches from being almost new to being almost gone.

The fighter Philo beat up at the meat packing plant can later be seen among the men at the Tank Murdock fight.



Factual errors

When the police officers are having target practice on the side of a New Mexico highway, two calls on their scanner refer to police activity on Interstate 5, the main major freeway between southern and northern California. Three interstates run through New Mexico: I-40, I-25 and I-10. The interchange in Albuquerque with I-40 and I-25 is called "The Big I."



Revealing mistakes

When the officer falls down at the lake and lands face-to-face with the rattlesnake, the glass separating the actor and rattlesnake is clearly visible.

When Philo is walking Clyde before they take Clyde to the zoo, the two of them walk in front of an adult theater and store in Denver, Colorado. Minutes later we see them driving toward Santa Fe, NM.



Miscellaneous

Two bass players are with Sandra Locke's country band in the bar. One standing up front and one sitting down by the drummer, which is somewhat unusual unless you are Spinal Tap.



Audio/visual unsynchronized

When the Black Widows surround Lynn Halsey-Taylor as she is driving out of the gas station, the sound of a pump-action shotgun being "racked" comes from the trailer. When the gang leader looks over, it's a double-barreled shotgun that doesn't need to be "racked" for loading.

At 1:09:54 a dog is heard to bark. A German Shepherd runs along in front of the cattle, but its mouth does not move like it should if it barked.

At the lake, when Philo jumps out of the tree, he stands up and does a Tarzan impression. He makes no sound until the view cuts to looking across the lake.



Errors in geography

At 1:05:00 Philo and Clyde are seen walking past a theater door located on Colfax Street in Denver, but shortly thereafter they are seen entering Santa Fe, New Mexico long before they reach Denver.