Glitter Rock - April 12, 1974 - S3-E17
Other mistake: During the album signing at the mall, a woman exposes her breasts to Sam. We see her from the front with Sam's hat covering her breasts. His hat moves just enough that you can tell she is wearing something covering her breasts.
Good Night, Dear Heart - November 9, 1957 - S2-E17
Other mistake: Sam opens Hila's diary to a page. The translated voice-over mentions the 4th of July, America's independence and how she met someone with whom she could fall in love etc... The actual text on the pages mentions only the "Beginning of July" and how "3 bears and a zebra were born in the zoo. "Anton" was there and told her about it. His entire family was there and had a lot of fun." The right-hand page mentions how they had a wonderful day visiting the castle at Chiemsee where they had lunch. (00:21:02)
Piano Man - November 10, 1985 - S3-E15
Continuity mistake: Sam is driving a beat up truck along a road and talking to Al about where Lorraine is. During this sequence it's foggy/smoky in almost all angles, except the view behind their vehicle. It's a shot of a sunny road. Where is the fog behind them?
The Wrong Stuff - January 24, 1961 - S4-E7
Factual error: Al says he was an astronaut and flew around the moon, describing a mission that sounds precisely like Apollo 8 (10 orbits around the moon, reading of Genesis, etc). In the season 2 finale episode 'MIA, ' set in 1969, Al says he was shot down in Vietnam two years earlier, in 1967, taken prisoner and not freed until 1973. The Apollo 8 mission flew in Dec. 1968, meaning Al would have been a POW at the time. Also, NASA astronauts aren't generally sent to serve as pilots in active war zones.
Double Identity - November 8, 1965 - S1-E6
Revealing mistake: Sam's reflection character turns around too slowly in the mirror at the beginning of the episode.
The Color of Truth - August 8, 1955 - S1-E7
Visible crew/equipment: The shadow of the camera is visible on the car's hood when Al is trying to convince Mrs. Melanie not to go after Sam. It lingers there for a while in the shot.
Double Identity - November 8, 1965 - S1-E6
Factual error: The episode takes place November 9, 1965. After the haircut incident they are seen moving away from a theater with Doctor Zhivago on the marquee, but the movie was released December 22, 1965, a month and a half after the scene is supposed to take place. (00:28:00)
Blind Faith - February 6, 1964 - S2-E5
Factual error: The episode takes place in New York in February. During the scene with the Beatles arriving at the theater, we see a tree that has very green and full leaves on it. Trees with green leaves are visible in other parts of the episode as well.
The Americanization of Machiko - August 4, 1953 - S2-E3
Factual error: The episode takes place in rural Ohio, however several times in the distance, large mountains are visible. Ohio has hills, but not large mountains.
Piano Man - November 10, 1985 - S3-E15
Revealing mistake: When Sam is driving the truck through the fog/smoke, Al tells Gooshie to center him on Lorraine but Al doesn't jump out. The shot cuts to a front view of the fog. The road noticeably jumps forward because there is a dissolve transition in this shot, even thought its the same angle. It's likely it was done to lengthen the shot.
8 1/2 Months - November 15, 1955 - S3-E12
Audio problem: Sam and Al are walking along the road when they come across the father of the baby. Sam tells Al that he's just a boy. Al replies that Sam is just a girl. Al's mouth appears to be saying "guy" or something else and the line is dubbed.
8 1/2 Months - November 15, 1955 - S3-E12
Continuity mistake: When Al is talking to Sam in the beginning about having to deliver the baby before he leaps, Sam gives Al a funny look. The scene cuts and instantly Al has a cigar in his mouth. We never see him put it in his mouth.
A Little Miracle - December 24, 1962 - S3-E10
Revealing mistake: The fractal of the star stops at a point just below the top of the frame, when in reality it should keep going. This gives away that the star is superimposed over the shot. Oddly enough, when it starts snowing, the effect looks normal.
A Little Miracle - December 24, 1962 - S3-E10
Revealing mistake: The video image over the building that Al shows Michael Blake is placed incorrectly. The edge of the effect is blatantly visible. This effect is corrected later when Blake asks to see the plaza again and the name is changed.
Maybe Baby - March 11, 1963 - S2-E20
Factual error: "Dancing in the Streets" by Martha and the Vandellas plays while the characters are driving. The problem is, the episode is set in 1963. That song was released in 1965.
A Portrait for Troian - February 7, 1971 - S2-E11
Factual error: When the second earthquake happens, certainly we would see evidence of the water shaking but the water is calm. In a real earthquake, the water would be sloshing around.
Disco Inferno - April 1, 1976 - S2-E2
Audio problem: When Chris is performing, and we see his dad watching, one of the scenes has poor audio sync. The music is ahead of his singing.
Disco Inferno - April 1, 1976 - S2-E2
Continuity mistake: Sam is buttoning up his shirt while at the bar. His hands are about halfway down his shirt. Cut and we see him from another angle. His hands are now down.
Play It Again, Seymour - April 14, 1953 - S1-E9
Revealing mistake: Sam opens his left hand when talking to Al at the beginning. His reflection does not. His reflection just points his finger.
The Right Hand of God - October 24, 1974 - S1-E4
Continuity mistake: Near the beginning, Sam has a cut on his left eye from the fight which they apply a bandage to later. The cut briefly disappears when Sam is talking to the sister, only to reappear.
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