When Lister first appears in miniaturized super-human form, he does not cast a shadow on the floor even though the other characters do.
When Lister first gets snared in the light of DNA machine the set can be seen to the left of the frame.
When first discussing his new humanity with Lister, Kryten thinks that humans need electricity to recharge and has to be told that humans recharge by eating sleeping. Kryten is a service droid and would have been programmed with this knowledge.