Continuity mistake: In the hotel Christopher Walken attaches the chain lock on the door. Camera angle changes and it is not locked, then locked again when the shot changes back.
Continuity mistake: When the robots are chasing the girls, the girls are all carrying make-shift Molotov cocktails made out of petrol cans with a rag in the neck. Suzie is hit in the leg by a robot and falls to the ground. The robot then fires a laser at the petrol can by her, causing it to burst into flames, which cover her too and burn her to death. However, when the camera pulls back, we see that her petrol can is mysteriously intact and untouched by the flames.
Continuity mistake: To reach Poirot, Hastings walks through the Acapulco airport with two ladies (one with a white jacket, light blue skirt, updo, carries a large brown suitcase, and another one with short hair, glasses, white trousers) that are both in front of him AND behind him, depending on the camera angle. (00:01:30)
Continuity mistake: After the car accident, a man in a black hat and coat runs up to the left-side rear window of Patton's car, taps on the glass, then peers into the car. The camera angle changes to show the Jeep arriving and we see the same man in black arrive again to repeat all the same moves exactly. (01:13:30)
Continuity mistake: Jane Fonda gets out of Jeff Bridge's car in broad daylight, but when she enters the dead man's house, it's night-time.