In this episode titled "The Handcuffs" Lucy handcuffs herself to Ricky with what she believes are Fred's "trick" handcuffs. The cuffs turn out to be real ones from the Civil War era and, surprise, surprise, there is no key. When the couple tries to go to bed, there is an hilarious sequence of events as they try to get comfortable, and at one point Lucy wants to take off her jacket, which of course is impossible because of the handcuffs. However, when the locksmith arrives the next morning Lucy's jacket is gone.

I've seen this particular episode numerous times over the years, but didn't notice this slip-up until its most recent airing.