The Night of the Tottering Tontine - S2-E16
Plot hole: They said they couldn't leave the room because the door wouldn't open and then they all went to their rooms. How did they get out?
The Wild Wild West (1965)
1 plot hole in The Night of the Tottering Tontine
Starring: Robert Conrad, Dick Cangey, Ross Martin, Whitey Hughes
The Night of the Avaricious Actuary - S4-E11
Continuity mistake: The letter from the Cyclops Insurance Company that Gordon pulls out of his pocket is folded, wrinkled, and well-worn. In the close up of the same letter West reads, the letter is white, pristine, and not wrinkled or folded.
The Night Dr. Loveless Died - S3-E4
Trivia: Dr. Loveless' uncle's name, "Liebknicht", is, aside from the addition of the letter "k", German for "Loveless".