Continuity mistake: In the scene where Bette Davis has lost her shawl there is a shot of her and Maggie Smith from far away. They talk about the time and in the background Angela Lansbury is drinking. She puts down her glass and leans her head on her hand. Then the shot changes to a close-up of Bette Davis and Maggie Smith and you can see Angela Lansbury in the background, with the glass in her hand, just about to take a drink.
Visible crew/equipment: In the scene near the start of the movie when Lois Chiles is showing Mia Farrow her bathroom and Mia Farrow is saying "Yes, It's lovely," on the mirror on the right you can see a member of the crew crawling around on his hands and knees. This is visible on the DVD as well as at the cinema. (00:05:50)
Plot hole: According to the denouement sequence shown in the film, Linnet Ridgeway is shot asleep in her bed approximately three minutes after retreating from the lounge. Less than 2.5 minutes pass from the moment Linnet leaves the lounge to the moment when Doyle is left alone by the other guests. It takes another 30 to 45 seconds for him to pick up the pistol, rush into his cabin and kill his sleeping wife. How could Linnet have walked to her cabin, taken off her jewelry, changed into her night-dress, retired to bed, and fallen asleep in 180 seconds?
Factual error: After Linnet Ridgeway had almost been crushed by a stone falling down from the temple of Karnak, Dr. Bessner advised her to go back to the boat to have a rest. She replied that it can be for just a couple of hours, as she must see the temple of Abu Simbel in the evening. In the next scene, she is really visiting Abu Simbel together with Simon and in the late evening they are back on the Nile steamer. This is absolutely impossible, as the distance between the temple of Karnak and the temple of Abu Simbel is about 400km (250 miles). By that time, it would have been impossible to manage 800km (500 miles) within one afternoon just for a visiting tour. And it is not very logical, as the Nile steamer was going up the Nile to Wadi Halfa, so they would have passed Abu Simbel anyway later during their trip. (00:47:00)
Factual error: In the Abu Simbel scene, watch closely when they show a side-view shot of Jackie, accidentally depicting the shores of Lake Nasser in the background. This reservoir was built only in the 1960s and didn't exist at the time the movie is set in (1930s). (In fact, the whole temple had to be cut from the rock and moved to higher ground following the completion of the Aswan Dam, so the "original location" was no more available for the film crew.)
Continuity mistake: Take a look at the Karnak temple scene when the massive stone block is pushed off the column to kill Linnet. Seconds before the stone falls, the column and parts of the floor beneath are brightly lit by the sun. Also notice that the stone is positioned maybe 2 yards off to the right of the column's centre. When the stone is coming down in the next shot, most of the column (and the ground) is suddenly in the shade. And when the stone hits the ground it is no longer positioned to the right of the column but in front of it.
Factual error: The body of Louise (the maid) is discovered when the room-service guy drops a towel on the floor and it lands in a pool of blood. The blood obviously ran out of her cabin from under the closed door. However, the cabin door thresholds are not at level with the floor (neither outside nor inside the cabins), but several inch higher, so her blood could not possibly have escaped through the cabin door. All along the movie you can see the actors carefully stepping over those irritating thresholds in order not to stumble, though I think it is hard to spot the edge from within Louise's cabin. But watch when Dr Bessner enters her cabin to investigate the body, it's pretty obvious he takes a step "down".
Continuity mistake: At the end, when people leave the boat, as seen in the wide shot, the wood plank is at a different distance from the stair's handrail than when Rosalie Otterbourne and Ferguson leave the boat.