Catch A Falling Star - May 21, 1979 - S2-E10
Continuity mistake: The makeup lady puts a moustache on Sam right after he leaps into the man. A stagehand bursts in, telling him it is time to go on. The moustache is now gone, and the makeup lady puts it back on Sam's face.
What Price Gloria? - October 16, 1961 - S2-E4
Continuity mistake: When Sam goes out of the window to save Gloria, part of the ledge breaks off, but in the near shots it is broken off almost to the corner near Gloria, while in the shots from below most of the ledge is still intact. (00:35:45)
Catch A Falling Star - May 21, 1979 - S2-E10
Continuity mistake: When Sam is going on stage near the beginning, another guy peels off his moustache and says "imposter." The problem is, the makeup lady already removed his moustache earlier in the episode.
Freedom - November 22, 1970 - S2-E16
Continuity mistake: Sam is talking to Al in the desert about what year it is. Al's cigar jumps in his mouth and back to his hand.
Jimmy - October 14, 1964 - S2-E8
Continuity mistake: Near the end of the episode Michael Madsen's character attempts to run over Sam with a forklift, causing the boy to fall into the water and almost drown. As the boy is falling into the water, there is a wide shot of the action. In the scene, a box is being pushed over the edge into the harbor. In the close shot following, the box is gone, as are other items nearby.
Her Charm - September 26, 1973 - S2-E15
Continuity mistake: The rearview mirror on Nick's car disappears and reappears repeatedly, when he pursues the laundry truck and later at the cabin.
Another Mother - September 30, 1981 - S2-E13
Continuity mistake: When Sam uses martial arts against the men from the van, one of them pulls a knife as he kneels on his right knee in the close-up, but next shot he is kneeling on his left knee.
Another Mother - September 30, 1981 - S2-E13
Continuity mistake: When one of the sicko men from the van pulls a knife on Sam, the white blouse is either tucked into the skirt or hangs over it, depending on the shot.
A Portrait for Troian - February 7, 1971 - S2-E11
Continuity mistake: When she's confronting her brother on the dock, Troian's long hair shifts from being completely behind her back to falling over her shoulders in front with each change of camera angle. (00:35:00)
Chosen answer: Per the Quantum leap page at http://www.scifi.com/quantum/episodes/season5.html. 8 August 1953: An enigmatic leap lands Sam in a Pennsylvania tavern, as his own grown self on the day of his birth. As Al and Gushie work frantically to locate him, Sam befriends a wise bartender (popular character actor McGill, who'd appeared in a different role in the very first "leap") and a group of coal miners. As a host of familiar-looking faces pass through the bar - with different identities than Sam remembers - Sam ponders his life of leaping with Al the bartender, who tells Sam he controls his own destiny. Pressed for more, Al the bartender simply shrugs and says, "Sometimes, 'that's the way it is' is the best explanation." Sam realizes he must right at least one more wrong before he can go home, and leaps back to tell Al Calvavicci's wife Beth (from "M.I.A.") to wait for Al, who will survive Vietnam and come home to her. The closing title cards state that Beth and Al have four daughters and will shortly celebrate their 39th wedding anniversary ... and that Sam Beckett never returned home.
Boobra