Visible crew/equipment: As Servalan begins explaining her nefarious plan to the captured Avon, an equipment shadow slides across the blue diamond-shaped pane just behind her. (00:40:30)
Revealing mistake: To conceal their unauthorized entry into the secret lab, Cally very carefully closes and locks the sliding door. But when she turns back to speak with Tarrant, the "secured" door rolls halfway back open by itself. No, it's not Servalan's troops sneaking in to catch them: there's no sign of anyone there. Besides, anyone unlocking the supposedly-locked door would have alerted them. A case of malfunctioning BBC scenery, plain and simple. (00:43:45)
Plot hole: If the "Enzyme Activity" adhered to the hull of the Liberator, how did it enter the ship without causing a hull breach and immediate loss of pressure ? Also, how did Servalan not suspect anything when she boarded, missed Orace and ordered Maximum Power surrounded by green mould?