Plot hole: Near the end of the episode Rimmer, Kryten and Lister are all in a Mexican standoff, each facing two shapeshifters who are impersonating them. The trouble is, thanks to Kryten's previous intervention Lister is now a soulless, unfeeling killing machine. Earlier he shot and killed a shapeshifter who could well have been Cat - he didn't know it was a shapeshifter and by his own admission he didn't care. We have already seen how fast on the draw he is - why didn't he just open fire on the six shapeshifters, Kryten and Rimmer in order to ensure his own survival? Don't tell me he was worried about being shot himself - fear is an emotion, too.
Plot hole: At the end, Kryten, Rimmer and Lister are in a lift facing off six gelf shapeshifters, two mimicking Lister, two mimicking Rimmer and two mimicking Krtyen, in a Mexican standoff. Nobody knows who to shoot, as they might shoot the real person instead of the shapeshifter. The problem is that Lister, Rimmer and Kryten are all self aware - they each know they are not a shapeshifter. All Lister has to do is shoot the two fake Listers, Rimmer shoots the fake Rimmers and Kryten shoots the two fake Krytens, problem solved.PEDAUNT