Confidence and Paranoia - S1-E5
Revealing mistake: After Lister faints, you can see him smirk when the cat sings 'S-E-X, I think I've found it!' (00:08:50)
Revealing mistake: Shortly after the fight with Becky, Roseanne asks Jackie to go across the street to get her something to drink, so she can smoke in secret. After Roseanne lights the cigarette and walks near the register, Jackie's plaid coat can be seen in the door's window as she waits for the next scene.