The Bird Who Knew Too Much - S5-E5
Continuity mistake: When Mrs. Peel drives to Jordan's house, she parks in front of the house. When the assassin arrives shortly after, her car has disappeared.
Factual error: The bad guys are supposedly auctioning off the stolen Mona Lisa. But they and their prospective buyers aren't very art savvy. The painting is more than twice the size of Da Vinci's actual masterpiece. (00:44:50)