Continuity mistake: When Prometheus is taking off near the end, you see Vickers getting up in the shot with the captain, then it switches to the close-up of her, and she is getting up again.
Continuity mistake: When Charlie gives Ellie a rose, the stem starts out long, but when he puts it into a cup the stem is half the size.
Continuity mistake: During the final scenes, after the ships have collided and crashed to the surface, Elizabeth finds David's detached head inside the alien ship. She then takes the head with her to a ledge where she is about to lower David's body to the ground. In both places, David's hair keeps changing between shots: messy/neat/very messy, with no logic whatsoever.
Continuity mistake: When Shaw is on the planet surface towards the end of the film, she isn't wearing any gloves. Later on, she suddenly has gloves again.
Continuity mistake: The 2 who are left behind to spend the first night there, due to the storm, are sprayed with a horrible spray when one cuts the alien creature as it wraps around the second's arm. They both get spray on their faceplates, but in the next shot the one that hasn't got it wrapped around its arm has no spray on his faceplate.
Continuity mistake: When Vickers enters Peter Weyland's room to speak to him just before he embarks to see the engineer, her hands are clasped behind her. They remain that way in each shot where she is seen from behind. But every time the camera angle changes and we see Vickers from the front, her hands are suddenly clasped in front of her. This switching occurs repeatedly throughout the scene.
Continuity mistake: As the group is getting into their survival suits before going to make contact with the last engineer, Shaw is talking to David and bends over in pain in a medium shot. The camera then goes out to a master shot, where Shaw is suddenly upright and bends over again.
Continuity mistake: The alien's spaceship falls from the sky and crash in the ground with its bottom facing one side. It rolls to Meredith Vickers and Elizabeth Shaw. But it faces the other side after crushing Vickers.
Continuity mistake: Prometheus is flown into the alien spacecraft, presumably to disable it from flying. However, after the alien craft has crashed and rolled over Meredith Vickers, the ship is facing face down on the planet, giving us a full shot of the back of the ship. There is no damage to the back of the bulkhead whatsoever, even after the bright explosion in the atmosphere. (01:43:00)
Continuity mistake: Upon entering the alien ship, Shaw can be seen holding a single-bulb flashlight, right after Fifield begins howling as he releases his "pups". But later on when Holloway notices the CO2 levels, she is holding a triple-bulb flashlight.
Continuity mistake: After Elizabeth tells Janek the engineer is headed for Earth and it needs to be stopped, Vickers shouts to Janek, "Captain, let's go." Janek is then shown looking downwards with his lips clenched shut and his eyes are clenched a bit. In the next shot, his mouth is suddenly open and unclenched, looking straight forward with no time to do so.
Answer: It's a matter of opinion, but watching the first Alien film gives enough of the necessary back story to understand Prometheus. However, it's possible to watch and understand Prometheus without seeing any of the other four Alien films. I would only recommend watching Alien 1 and 2.
raywest ★