Deliberate "mistake": Because Stephen Greif tore an Achilles tendon playing squash, a stand-in had to complete his scene with Servalan in Ensor's underground complex. The result was a very odd segment in which we hear Travis' voice (pre-recorded by Greif) answering Servalan's lines, but never see him - except for an awkward shot of shuffling, black-booted feet that are all-too-obviously not Greif's.

Visible crew/equipment: At the end, when Blake says "The other end is connected," the boom shadow crosses Avon's face.

Revealing: As Liberator approaches it, the planet changes color.

Plot hole: When the newly-acquired Orac is first set up on the flight deck, Blake comments that "the other end's connected." Connected to what? Orac didn't require plugging in, other than putting his activator key in place, and that was never connected to anything else.

Continuity: When Cally puts her teleport bracelet on in the teleport room, it's on her right wrist. After she and Blake materialize on the planet's surface, the bracelet has mysteriously moved to her left wrist instead.

Revealing: When the "phibian" lizard creature attacks Servalan, note the claw that grabs her leg: it is obviously made out of soft fabric and visibly bends as it latches on.

Visible crew/equipment: When Avon calls and wakes Vila up, ordering him to the teleport room, you can see Vila, who's supposed to be in his quarters at this point, hiding in the corridor waiting for his cue.