Corrected entry: It has already been proven that the Teleporter picked up from the Simulant ship in Rimmerworld has the ability to transport both time-and-space: Kryten accidentally sends himself, the Cat and Lister back in time a week (and then later, forward several weeks) while at the same time transporting them back to the 'bug. If that were so, why would they be interested in a Time Drive?
Corrected entry: When it is believed that Lister is a droid, why does Kryten be so rude to him, considering that this is the same person who helped him override the program preventing him from lying to humans? Also, wouldn't he have realised that Lister came out of Stasis with a long beard and nails? These wouldn't grow on droids.