Good Morning, Peoria - September 9, 1959 - S2-E6
Factual error: While it's done for furthering the plot, climbing a live AM radio tower would result in RF burns and would possibly be fatal. The man who cuts the transmission cable would be in a lot of pain or dead doing that in real life.
What Price Gloria? - October 16, 1961 - S2-E4
Revealing mistake: When Sam is getting ready with the other woman, the shoes on the floor do not match in the reflection. Their position is off.
What Price Gloria? - October 16, 1961 - S2-E4
Revealing mistake: Sam and the other woman are staring at their reflections while Sam is getting ready. Notice where the woman with darker hair is standing in relation to Sam. Their mirror images are further apart. The woman with darker hair also has her head tilted to the right slightly. Her mirror image doesn't.
Play It Again, Seymour - April 14, 1953 - S1-E9
Revealing mistake: Sam is getting shot at in the aircraft hanger. He hides behind a yellow machine and a bullet hits it. The bullet produces a flash but leaves no mark where it hits. A real bullet would have left a gash at the least.
Disco Inferno - April 1, 1976 - S2-E2
Factual error: The episode takes place April 1, 1976, and Sam performs a stunt for the "Earthquake" movie featuring Charlton Heston, but Earthquake was released in 1974, so was filmed long before 1976.
Honeymoon Express - April 27, 1960 - S2-E1
Factual error: The date is April 27, 1960, and Al says the Francis Powers U-2 spy plane will be shot down in two days, namely April 29, but the plane was actually shot down on May 1, 1960, four days after the episode.
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.
Runaway - July 4, 1964 - S3-E11
Revealing mistake: The family crosses into Colorado from Wyoming and calls out the state names. Wyoming doesn't have Joshua trees, nor anything close to the desert we see. This episode was filmed in Southern California.
Animal Frat - October 19, 1967 - S2-E12
Audio problem: A dog runs by Sam chasing one of the frat pledges. It's barking according to the audio, however the dog does not bark.
Maybe Baby - March 11, 1963 - S2-E20
Factual error: Across the street from the general store where Sam and Bunny escape is an AllState Insurance office. The logo for the store is the more modern 1990s logo. The 1960s AllState logo had a different appearance.
Factual error: Many of the episodes are set in the 1950's or early 1960's, but we always see three-prong electrical outlets in the buildings. Three prong electrical outlets only came into common use in the mid to late 1960's, and were required starting in 1969. While they existed before that, they were only installed in specific use situations.
Pool Hall Blues - September 4, 1954 - S2-E18
Factual error: After Eddie tells his helper to get rid of Sam's/Charlie's pool cue Alberta, we see an exterior street shot with an elevated subway going by, with a lot of 1970s and 1980s cars parked and driving by. Not quite appropriate for the 1954 setting. (00:35:40)
Good Night, Dear Heart - November 9, 1957 - S2-E17
Revealing mistake: When Sam is talking to the sheriff in the parlor and says it can't be prosecuted, he walks in front of a mirror and we see the real doctor in the mirror, except we see the real doctor standing up just as he becomes visible, and Sam's shoulder just to the left. They used the mirror's angle to fake the mirror image, and probably panned the camera over the other actor's head as it swung around which is why he had to stand up. (00:38:40)
Play It Again, Seymour - April 14, 1953 - S1-E9
Continuity mistake: The cut on Sam's face from the bullet is larger than the one on his counterpart's face.
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