Plot hole: If everything goes backwards, shouldn't Kryten and Rimmer have got fired, done their job and then got hired? Rimmer & Kryten discovered that everything was backwards in the cafe earlier in the episode. At the club they did their act and then got fired. Put this 'forwards' and it becomes wrong.
Other mistake: It is established in the backwards version of Earth, that all writing is reversed and is spelled backwards. However, there are some inconsistencies, as in some instances the writing has been mirrored to appear reversed, whilst in some instances the writing has just been spelled out backwards. For example, car number plates and signs on display in the background have been mirrored to appear reversed, but the newspaper that Kryten reads, the Nodnol sign and the Sensational Reverse Brothers poster appear normally typed out, and not as the mirror image that other aspects of this world have.
Revealing mistake: When Rimmer stands up from underneath the table, just before he says, "Thanks for your support" to Lister, listen very carefully and you can hear the stunt director saying "Action!" backwards. This shot was the splice point between the reversed and the regular footage. (I know this mistake is listed as being in the 'backwards version' on the DVD, but it is in the regular broadcast version too - you just have to listen harder for it.)
Revealing mistake: At the start in the cockpit of Starbug, the green screen behind Lister is visible instead of the painted starfield that should be there. (00:02:35)
Suggested correction: That is because Starbug is parked inside Red Dwarf at the time, and the stars wouldn't be visible.
Continuity mistake: After Starbug and Blue Midget leave Red Dwarf, there is a shot of Blue Midget driving away from the ship, towards the camera. Cat and Kryten are the only two on board as Rimmer and Lister are on Starbug, but there are three people shown inside Blue Midget. This is because the shot was taken from series two, in which Rimmer, Lister and Cat were inside it. (00:03:25)
Visible crew/equipment: If you look closely when the camera follows Lister (in the scene just before the meteor crashes onto Starbug) you can actually see the edge of the set and some studio lights. (00:04:10)
Other mistake: When the meteor hits Starbug, there are no stars outside the front of the ship at all. (00:07:20)
Continuity mistake: When Lister is telling Rimmer that he is going to die and that Rimmer doesn't need food, there is snow over his face, hair and coat collar, but a few seconds later, the snow has mostly disappeared. (00:09:35)
Continuity mistake: At the start of the episode, it is clear that the capsule fully rotates and the "contents: 2" sign is not on the capsule. (00:01:05)
Continuity mistake: At the start of the episode when we first see the polymorph, it looks into the mirror, then covers its eyes. Yet when we see the reflection, it already has its hands over its eyes before it gets to the mirror. (00:01:30)
Continuity mistake: When the Polymorph is switching between various appearances at the start, it stops at a rabbit. When the Polymorph stops at the rabbit, there is a damp stain beside the two yellow lines on the floor. This damp stain was not there when the Polymorph was switching between other forms. The stain just suddenly appears out of nowhere. (00:01:45)