The Night of the Plague - S4-E24
Continuity mistake: The last scene shows the back of the boxcar amid dirt and brown/mustard colored short grass. When Ms. Averi Trent opens the door to meet her fiancé, we see a lush green tree by the door.
The Wild Wild West (1965)
201 continuity mistakes - 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 of the Infernal Machine - S2-E14
Trivia: West collides with the cook and sends him sprawling face-down in a huge platter of gelatin. Before racing off again, West quips, "Sorry about that, chef!" This was a winking homage to the 60s spy comedy Get Smart and its bumbling hero Maxwell Smart's famous catch-phrase, "Sorry about that, Chief!" (00:47:30)