The Night of the Headless Woman - S3-E17
Continuity mistake: When West comes out of the water, he is soaking wet, but when he sneaks onto the stagecoach and fights with the driver, both his hair and clothes are dry.
The Wild Wild West (1965)
1 continuity mistake in The Night of the Headless Woman - chronological order
Starring: Robert Conrad, Dick Cangey, Ross Martin, Whitey Hughes
The Night of the Brain - S2-E21
Revealing mistake: Mr. Braine screams as his steam-powered chair crashes into the bandstand. If you look closely at the next shot, just before the explosion, you can see that the dummy now in the chair has its head bowed forward. It also has light brown hair, rather than Mr. Braine's silver hair. (00:47:10)
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".