In the first scene Legion appears, the tube on top of his head is not tucked into his mask, but in all the following scenes it is.
Legion removes Lister's appendix, but in the series 2 episode 'Thanks for the Memory' it is revealed that he already had it removed.
As the Cat says, "The entire panel's deader than A-line flares with pockets in the knees", you can also see Lister mouthing these words at the same time.
When Legion stabs his left hand to make the crew feel pain, everyone grabs their left hands except Lister who grabs his right hand.
"1992" can be seen on a page of the magazine Lister is reading when he complains that someone's already filled in the memory test. The cover has "Zero Gee" printed on it, so it's supposed to be about Zero Gravity football, a space-age sport presumably invented long after 1992.
When Kryten, Lister, Cat and Rimmer are discussing how to get out of Legion's ship Lister nearly has an empty glass, yet when he picks it up and asks Cat for caviar it is full again.
When they are sitting at the table for the second time, a camera is briefly visible half way up the left side of the screen.
Top right of screen when Lister says "You have a longer yellow streak than a line of diuretic camels."