Corrected entry: When Arthur and Ford get flushed out of the Vogon ship, the airlock's exterior hatch changes from a sliding design (as seen inside the airlock) to a hinged design.
Corrected entry: After Arthur presses the "manual improbability control" button which turns the missiles into a whale and a bowl of petunias, Trillion is wearing red trousers. She was wearing a red skirt before Arthur pressed it.
Correction: Compared to turning missiles into a whale and a bowl of petunias, changing somebody's clothing is relatively minor.
Corrected entry: When Ford checks the escape pods, Zaphod is holding a shoe up, which you're supposed to asume is the end of Ford's leg. But you can see the inside of the shoe. What's more, when he drops it, you hear Ford fall but don't see him.
Correction: Ford's leg is there, it's just black so it's hard to see. And when Zaphod drops him, he throws him to the side.
Corrected entry: Arthur and Ford find the ultimate question by taking letters at random from a Scrabble set - spelling 'What do you get if you multiply six by nine' - and the words 'Forty' and 'Two' are already on the board. That is five Ys - and there are only two Ys in a Scrabble set.
Correction: They are playing with Arthur's homemade Scrabble set, not a standard one, so he could add as many of each letter as he wanted.
Corrected entry: Before Zaphod, Arthur, Ford and Trillian enter the lift after talking to the mice, Trillian wears a dull red suit which hasn't been done up much. However when they leave the lift Trillian's suit is shiny and is considerably more done up. Her suit stays like this until in Episode 5 after the book explains Milliways when it suddenly changes back.
Correction: She is wearing a shiney red jacket over the top of her spandex. As they land on the planet and are walking to the airlock on the ship, you can see her carrying it.
Correction: Actually, it would make quite a bit of sense that there are two doors. If one develops a leak, the other can still keep the air in.