Revealing mistake: The dead cop can be clearly seen sitting up even though he's dead as the lady cop tosses the chair through a window. The next shot he's back to being dead again. (01:16:00 - 01:17:15)
Visible crew/equipment: When Mel Gibson is getting his red boat ready to put in the water, his friend comes out of his house to talk to him. You can see the camera crew reflected in his friend's sunglasses.
Continuity mistake: When Larry and Rocket are about to go one-on-one in a shoot-out, the car behind Larry is empty. When the shooting starts, the car is full of people. (01:46:20)
Revealing mistake: The "Great Train Robbery" actually took place on a two-track railway near Cheddington - the West Coast Main Line. However, the filming took place on the Great Central Railway steam line near Loughborough, which only had one track at that time. They laid a second track for the filming, but omitted to cut down a large tree at the end of the rails, which would block the path of a train. This is blindingly obvious, especially as they show this "atmosphere shot" twice. The tree is still there the second time.
Continuity mistake: When Beau Bridges runs past the hooker on the street he has no bow tie. In the next scene as he approaches the telephone booth, the bow tie is back and he removes it after entering the booth.
Continuity mistake: After the will was read, Mrs. Boynton tells the 'children' that she has a lovely surprise. Carrie Fisher in the wide angle changes position leaning her chin against the back of her hand, and repeats the gesture in a subsequent shot. (00:04:15)
Factual error: The timeline is flawed. Baseball season typically runs Mar/Apr through Sept/Oct - Michael was on teams in FL then NJ. The Spartanburg newspaper article Harry was reading the morning after the Popes fled FL was dated Mar 19, 1987 - Spring. Travelling to NJ as well as during the Popes' stay there, all tree leaves were green - Summer foliage. After asking Michael where he was applying to college, Lorna told him he'd have to apply next term - meaning January. So, was it Spring, Summer, or Fall?
Other mistake: When translating Dutch for English, one translation uses "their" when it should've been "there." It's in the scene when we first see the lead cop talking to his daughter.
Revealing mistake: Clearly not Susan Blakely when she goes topless. Her hair suddenly becomes curlier, that's a body double.
Continuity mistake: When Chris has a gun aimed at Evelyn he's holding it with his right hand. A shot behind him and suddenly it's in his left hand.
Factual error: The Los Angeles cops pursuing Lulu, Peaches, and Darlene in Mexico couldn't arrest them due to this being a foreign country where they wouldn't have jurisdiction.
Revealing mistake: When Jemma enters the headshrinker's laboratory, there is a table with three heads on it each encased in glass. When it goes in close-up on the middle head, you can see that the table has a hole where the actor can slip in his head.
Factual error: The events in the film take place in mid-1929, as evidenced by the first Academy Awards being presented in May. However, Wyatt Earp went to the happy hunting grounds in January of that year.