Revealing mistake: At the beginning of the film, Stan reverses the bus into the manager's car. While the manager is under the bonnet looking at the engine, causing it to fall on him, you can see a rod with padding on it to stop the bonnet from hitting the manager. It is gone in the next scene.
Revealing mistake: After Hooker escapes the attack by Lt. Snyder in the phone booth, he runs down an alley. On a cross street in the distance, a modern sedan and large white truck drive by.
Revealing mistake: When Barbara Windsor is fighting Margaret Nolan in the Hotel Lobby, they jump onto a sofa and it falls backwards. If you look carefully, the lady seated on the sofa can be seen helping it fall backwards with her foot.
Revealing mistake: When Jack Hawkins punches through the door it is very apparent that it's made of very thin wood to make it much easier to hit through.
Revealing mistake: At one point John is complaining about the Beach Boys playing on his car radio, he reaches to the center console and motions turning the radio off. In a few other shots though, we see that the car appears to have no radio at all, the center console seems to have a large tachometer and speedometer there, but that's all.
Revealing mistake: Diane Keaton's stunt double is obviously a man during the scene where Luna swings across the stream and into a tree.
Revealing mistake: At the beginning of the movie, the coked-up sailor is shooting from a rooftop and screaming various racial slurs. Despite that, there's a big crowd building. When he shouts "Come and get me, honkies!" you can see people running way before he pulls out of the gun again and shoots. Not only that; some of the extras are just enjoying themselves and not keeping a straight face, far from being scared. (00:01:00)