Continuity mistake: When Vargas beams up to the Liberator just ahead of Blake, Gan & Vila, he challenges them when they arrive from the other side of the room - by stepping out of the teleport bay. But they're standing in the teleport bay, and Liberator has only one. So exactly where is Vargas standing?
Revealing mistake: Stock footage of the London's launch from Earth is run in reverse when it lands, supposedly 8 months later, on Cygnus Alpha. What are the odds that a remote penal planet will have a launching pad with configurations, lights, buildings and background terrain all completely identical to the launch stage on Earth?
Visible crew/equipment: That main console! The uppermost of the flight consoles of Liberator isn't fixed down in this episode, and wobbles almost every time it is touched, and not just small wobbles. Watch for the 10 seconds or so after Jenna says "Eventually I might just be able to get her to start and stop", and you'll wonder how she didn't knock the entire prop off whatever it's sitting on and onto the floor.
Plot hole: When the Liberator returns to the planet, Travis remarks that their orbit is too far away to use their matter transmitter. Since Travis had only found out that they even HAD a matter transmitter (which the Federation hasn't managed to develop yet) when he spoke to a technician just before that, how would he know what the range was?
Continuity mistake: At the end of "The Way Back," Blake, strapped in his prison ship seat, looks over his shoulder at the window behind him as the ship leaves Earth. This same scene is recapped at the beginning of "Spacefall," only now Blake is sitting one seat to the left of the window instead of directly in front of it.