Plot hole: Shortly after the ship flips over, the steward, Acres, is asked why lights are on. He explains they are emergency lights that will last three hours. The lights are left on throughout the movie, but when they get out it is bright daylight. Considering the ship flipped at midnight, there is nowhere on any ocean where it gets light at 3:00 in the morning.
The Poseidon Adventure (1972)
1 plot hole - chronological order
Directed by: Ronald Neame
Starring: Gene Hackman, Leslie Nielsen, Ernest Borgnine, Shelley Winters, Red Buttons, Stella Stevens, Carol Lynley
Visible crew/equipment: When Rev. Scott swims up the first stairwell, after pushing aside the dead crew member, as his head comes up the shaft, you can see, very quickly, the flippers of a crewmember swimming out of the shot behind him. (01:22:55)
Mrs. Belle Rosen: You see, Mr. Scott? In the water I'm a very skinny lady.
Trivia: The look of the set for the upside down engine room was so real, the actors refused to climb anything, fearing that it would fall. The set designer and builders had to climb it first to prove it would hold.
More questions & answers from The Poseidon Adventure
Answer: Because he doesn't boil, there's no suggestion that the water is that hot. After Ackers falls in, and while Rogo tries to save him, there are two large explosions in the shaft; we can presume that, while Rogo was able to escape, Ackers was injured/trapped/otherwise incapacitated below the surface, and drowned.