Plot hole: There is a guard stationed in the time lock vault without oxygen. Also, if the vault was supposed to be that secure, why were there simple bars protecting the back entrance?
Continuity mistake: During the final fight between Jean-Claude and the bad guy, they are both holding onto a shotgun. Initially the barrel of the gun is in J-C's left hand. But without either of them letting go of the gun, suddenly the gun switches end-for-end and the stock of the gun is in J-C's left hand. It looks like they probably re-filmed the last of the fight so the bad guy could use his right hand to hit J-C with the butt-end of the gun.
Continuity mistake: When Arnie and Jay arrive at their grandmother's candy store to stay with her, their Aunt Bella is making ice cream sundaes for them. Watch the whipped cream and cherries on top of both sundaes, they go from melted to fresh again between shots.
Visible crew/equipment: When the love scene between Linda Fiorentino & Charlie Sheen happens they knock over a lamp but if you look closely a hand reaches out to grab it. (00:52:20)
Continuity mistake: As the young Navigator is going to catch the train, the Union Jack flag at the end of the platform is upside down.
Revealing mistake: The soldiers on the beach were armed with M-16 rifles. The movie period was 1962, during the Cuban Missile Crisis. The M-16 and M-16A1 were not manufactured until 1964.
Suggested correction: Just watched Matinee again after reading this. I saw M1 carbines, M1919A4 and M2.50 cal machine guns and M14 rifles. There are no M16 series weapons in this movie.
Other mistake: During the first fight scene just before you see Gege accidentally shoot his friend, Fritz goes off with another German to look for Russians. However, as he sets off you can see that he has no bullets in his gun at all! There is no magazine attached. (00:27:25)
Continuity mistake: When Chuck spills milk on Gloria, her face and hair get completely wet. She starts screaming and yelling at him up the stairs. When she does, she's completely dry and clean. She didn't have time to clean herself. Really obvious.
Deliberate mistake: Towards the end of the film, Josh is playing a game in the park with Vinnie, and Vinnie asks "What's that?", to which Josh replies "Schliemann Attack." However, this dialogue occurs while the game is still in standard opening theory and before Josh has played the move that introduces the Schliemann Attack (pawn to f5).
Factual error: When Sharon is being driven by her Dad to the hospital to give birth to her baby ('Snapper'), they drive over a bridge on the River Liffey in Dublin to the south side of the city. However, the Rotunda Hospital, where she gives birth is on the North side of the city, quite a distance away from where they seemed to be headed.
Continuity mistake: After Miranda sings for the hotel manager, her guitar case closes and zips itself in a split-second.
Continuity mistake: When Sheela, Pru and their two dates leaves the house, Giddy is seen sitting upright by the table. When it cuts to a close-up of Giddy, she leans onto the table while resting her head on her hand. (00:38:05)
Factual error: At the end of the movie they say that Bill Kraus died on January 26th, 1986 but he actually died on January 11th, 1986.
Revealing mistake: You can see the shadow of a camera and a microphone on Michael Biehn or Nicolas Cage back when they are fighting.
Revealing mistake: Right before Alex and Tommy are about to leave for their date, Walter is playing Tetris. When he puts down the control to come talk to them in the kitchen, the game keeps playing and you can see the pieces moving and turning.
Continuity mistake: In the scene where Ellen and Newland are seated in her living room by the fire, we see her take a cigarette holder charm off of her bracelet. Then, the next scene shows a closeup of the cigarette holder charm, and she is again removing it.