Visible crew/equipment: When talkie toaster says 'light speed' a crew member can be seen in its reflection wearing a yellow t-shirt and jeans. (00:17:35)
Visible crew/equipment: Just after Lister hits the toaster, a pair of legs can be seen moving in it's reflection a moment before the scene ends. (00:11:30)
Continuity mistake: Just before Lister cuts himself shaving, he is shaving away from himself. The camera changes and he is shaving in the oposite direction. (00:13:00)
Revealing mistake: In the drive room when Lister kicks the vending machine after he finds out he's going to die, you can see the shadow of the machine wobbling as if it were lightweight. (00:20:20)
Continuity mistake: The sign above the stasis booth in this episode is different than what it was in the previous episode, "The End". (00:14:00)
Continuity mistake: Both Rimmer and Lister go through a door on the right hand side of the captain's office which wasn't there in the previous episode. (00:10:20)
Continuity mistake: When the Cat's future echo says, "I think I lost my tooth," he is at The End of the corridoor. When the present Cat say it, he is just leaving the sleeping quarters. (00:16:30 - 00:22:25)
Audio problem: In Rimmer's future echo he says, "You're space crazy", but in the real conversation with Lister, he actually says, "You are space crazy". (00:15:20 - 00:16:15)
Revealing mistake: When Holly gives Rimmer a new uniform, during the switch, Holly can be seen to jolt on his screen in the background. (00:03:20)
Continuity mistake: When Lister is fixing his robot goldfish, he picks it up with his right hand, then after the camera cuts, he puts it back into the tank with his left hand. (00:06:00)
Continuity mistake: When Lister sees the future echo in the drive room, Rimmer points when he says 'Shut up.' However when the scene plays out again, Rimmer's arms stay down by his sides. (00:15:00 - 00:16:00)
Continuity mistake: When Lister rides his bike in the first scene, there is a Union Jack just behind his seat. When he stops, a US flag has appeared below it. (00:01:45)
Continuity mistake: When Lister cuts himself shaving he moves his locks behind his back, then in the next shot, they are over his shoulder again. (00:12:55)
Continuity mistake: The cuts on Lister's robot goldfish disappear when he throws it back into the tank after fixing it. (00:06:00)
Visible crew/equipment: Just before Rimmer sends his 'Internal Memo' Lister is standing next to his fish tank in the sleeping quarters. In the relection of the glass you can see pages being looked through by a member of the crew. (00:23:15)
Continuity mistake: At The End of the episode, when the future Lister and the babies appear, Rimmer has his arms folded. In the next shot, Rimmer's hands are on his hips. Also, Lister's locks change positions. (00:27:50)
Revealing mistake: When Holly gives Rimmer a new haircut, Rimmer salutes and touches his hair with his hand. Surely he would have noticed his hair has become much longer, especially after he asked for a crew cut. (00:07:00)
Revealing mistake: When Rimmer runs to Lister after Lister unsuccessfully orders a black coffee, the camera tilts.
Visible crew/equipment: When both Rimmer and his future echo walk through the door from the captain's office, the edge of the set can be seen. (00:15:09 - 00:16:04)
Revealing mistake: When the future echo Rimmer leaves the drive room and the actual Rimmer walks in, there is a visible line caused by the split screen effect, done to show two Rimmers onscreen at the same time.
Chosen answer: In-universe, after leaving Red Dwarf after his first appearance, Kryten managed to crash Lister's space-bike into an asteroid. Lister found his remains and decided to rebuild him, however, due to the high level of damage and Lister's questionable repair skills, he was unable to recreate Kryten exactly, leading to changes in appearance, personality and accent. In reality, the original actor wasn't available, coupled with presumably practical concerns about one-off makeup as opposed to makeup for a regular cast member, so some visual changes were made.
Tailkinker ★