Continuity mistake: Poirot met Ariadne Oliver who invites him to the "murder hunt." Poirot and Hastings then get on a boat to head there. As they sit on the boat, there are a few extras, led by an easily identifiable lady in a yellow sweater, that move up the stairs of the pier and reach the top. The boat slowly takes off, and about 10 seconds later we see the pier again, with again those same people from before just reaching the top of the stairs. (00:02:25)
Revealing mistake: The chairman parks his car in front of Bel Fuse Ltd. And goes upstairs. His car explodes, but does it in front of a different building, probably switching to a stage building front; the metal doors don't have vents anymore and there are visible join lines in the asphalt and the cement. (00:15:10 - 00:15:40)
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)
Other mistake: The subtitles of the international version translate a few things completely wrong, including, when the body of the warden is found, "There were three men!" instead of "It happened at half past three." (00:04:25)
Continuity mistake: When Rachel goes to the "group", her bag is multi-coloured; when she comes home from the "group", her bag is different, it is now just black.
Visible crew/equipment: In the opening sequence, Sammo Kam-Bo Hung is scavenging the dead soldiers (with one hilarious twist) - however, when he is holding the ring, in his sunglasses you can see several very much alive crewmembers standing. (00:02:45)
Other mistake: Lakella seems to disappear from the movie after the battle.
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)
Factual error: The movie as the opening captions say, is set in Melbourne, Australia, 1978. However when Sam at the beginning of the movie drinks the milk and moves to the other room where the TV is, he passes by a poster (a communist party poster, the Italian communist party, strangely enough) that was designed only in 1981. (00:09:25)
Visible crew/equipment: As Abe Vigoda pronounces the last line of the movie ("Take care, my friend"), a boom mike pokes up in full view from the bottom right of the screen.
Revealing mistake: When Louise pulls off Joel's trousers, we see that he is wearing briefs under his boxers.
Revealing mistake: When Eddy's mother is lying dead on the bed, she is breathing.