Accidentally Correct Writing: In "All-Americans" (which aired in 1990), Al tells Sam that the Pittsburgh Steelers are down by three points in Super Bowl XXX. When Super Bowl XXX was played in real life in 1996, the Steelers were down by three points on two occasions during the game, which they ended up losing to the Dallas Cowboys.
Actor Existence Failure: Narrowly avoided with Dennis Wolfberg as Gushie. He was being treated for cancer around the time of the series finale and he died a little more than a year after it aired.
Banned Episode: "Justice", which has Sam leaping into a Ku Klux Klan member, is consistently skipped over in syndication, no doubt because of the subject matter and frequent use of the "N-word".
Development Hell: There have been attempts since at least the early 2000s to get some kind of spin-off set up.
The Sci-Fi Channel announced in 2002 that they would produce a Quantum LeapPilot Movie featuring Sam's daughter Sammie Jo as a new leaper. A proposed release date of 2004 was given, and the movie's writer even gave a QL fansite an interview in 2004 about the plot, but ultimately nothing ever came of it.
Donald Bellisario announced a movie in 2010. As of 2019, this has yet to gain any visible traction past Don's pitch.
Following the pilot, episodes would open with a Sam voice-over and montage referring in some way to the previous leap. The series abandoned this convention roughly halfway through the second season — likely in order to make it possible to air episodes out of sequence. When the series went into reruns, this trope kicked in — with the stated openings being dropped. They were replaced with the familiar "...will be the leap home" opening narration and the "Oh, boy!" scenes.
In the summer between the first and second seasons, NBC ran a one time only 90 minute recut version of the pilot featuring only the first leap and editing out the baseball leap.
In reruns, the first three seasons always had the opening sequence made for Season 4.
In the version of the pilot aired on G4, the trademark lighting strike that came after Al's line "Yeah, well, you ain't Roy Hobbs either!" is missing. It's such a small cut that it doesn't seem to be made for time reasons.
One of the episodes Donald Bellisario was planning for Quantum Leap before it was canceled was for Sam Beckett to leap into Thomas Magnum, thus merging the Quantum Leap continuity with that of Magnum, P.I.. They apparently did film the initial "leaping in" scene, with Scott Bakula in the familiar red Hawaiian shirt turning to the camera and doing Tom Selleck's famous comical eyebrow raise from Magnum, P.I.'s opening credits. This would have resulted in a Celebrity Paradox, since in "Another Mother", Susan Buckner is seen watching Magnum on TV. However, according to the Starlog publication 100 Years of Science Fiction the plan was for Bakula to leap into the body of Tom Selleck as he filmed the series, not the character.
The original scene for the finale has recently resurfaced, showing instead of the infamous Black Screen Of Death, it showed a photograph of Al, Beth and their daughters in the present day.
Another planned leap that was never produced would have had Sam enter the body of ... a cartoon character?
In an interview conducted shortly after the series ended, Bakula was asked if there were any particular historical figures or events he would have liked to see Sam involved with. Bakula said he would have liked to have done something with the Kennedys unrelated to the assassination or relationship with Marilyn Monroe.
Carolyn Seymour plays Priscilla Stoltz in "A Portrait for Troian" and evil hologram Zoey in Season 5.
"Mirror Image" is partially built on this trope, with Sam encountering people that look like ones from previous leaps — John D'Aquino (Tonchi for Frank) and Richard Herd (Ziggy for Moe Stein). Notably, while Bruce McGill played both Weird Ernie and Bartender Al, Sam doesn't notice any familiarity.
Willie Garson played the title characters in "Play It Again, Seymour" and "Lee Harvey Oswald".
Olivia Burnette plays Susan Buckner, the older daughter of Sam's housewife leapee, in "Another Mother" and Sam's sister Katie in "The Leap Home".
Charles Rocket plays Michael Blake in "A Little Miracle" and Commander Riker in "A Leap for Lisa".
Sloan Fischer plays Dr. Daniel Young, the man in the mirror that Sam has leaped into, in "How the Tess Was Won" and the next season plays a stagehand in "Blind Faith".
Teddy Wilson plays two major supporting roles: Jimmy Grady in "Pool Hall Blues" and Ernie Tyler in "Rebel Without a Clue".
Quantum Leap has several references to producer Donald P. Bellisario's previous series, Tales of the Gold Monkey, including a character named "Gushie". "Ghost Ship" featured a Captain Cutter, which was the name of the main character in Tales of the Gold Monkey.
Sam has leaped into nine women: a secretary, a divorced mother of three, a beauty pageant contestant, a pregnant teenager, a rape victim, a singer in a teenage girl group, a housewife during the women's movement, Dr. Ruth Westheimer, and an inmate in a women's prison.
As far as any other leapers go, Zoey was the only other leaper to be seen leaping outside her gender, during her leap into Clifton Myers. Al's sole leap was into another man, and Alia's three onscreen leapees were all women.
Sam Beckett and show creator Donald P. Bellisario share the same birthday: August 8.
Sam has leaped out of the United States seven times: Egypt, Vietnam, a plane over the Bermuda Triangle, Japan, the Soviet Union, a raft in international waters, and England. If Virginia in 1862 is counted (as it was part of the Confederate States of America at the time), this brings the total to eight.
Sam leaped into the year 1957 seven different times, which made it the most leaped into year during Quantum Leap's entire run.
Sam leaped into every year from 1953 through 1987 at least once, except the years 1977, 1984, and 1986.
Quantum Leap came close to being canceled in its third season due to low ratings. However, a letter writing campaign helped save the series and enabled it to continue for two more years.
Sam Beckett is revealed to have attended MIT, and his friend and guide Al Calavicci is mentioned to have also spent some time there.
Al Calavicci drives two different Ferarris in the series: in "Genesis: Part 1", he is in a red Testarossa (which is shown from very low angles so as to keep the identity of the car hidden), and in "Killin' Time", he is driving a 512 BB Convertible conversion.
Ranked #15 in TV Guide's list of the "25 Top Cult Shows Ever!" (30 May 2004 issue).
The character of Sam Beckett was ranked #12 in TV Guide's list of the "25 Greatest Sci-Fi Legends" (1 August 2004 issue).
Season One's cliffhanger into Season Two was the teaser for "What Price Gloria?". The next season, three other episodes premiered before "What Price Gloria?" aired.
There were several ideas for episodes which ultimately were never used. One had Sam leaping in as Robert F. Kennedy. Another idea would involve an animated episode. The producers even toyed with the idea of leaping Sam in as a baby. Also, Donald P. Bellisario wanted to do an episode where Sam leaps in as Thomas Magnum (from Magnum, P.I.). It is unclear why that episode never materialized, although in an earlier episode, a character is seen watching Magnum, P.I., thus establishing that show as fiction within the Quantum Leap "universe".
Donald P. Bellisario's favorite of all his TV shows.
Scott Bakula ad libbed the line "Oh boy!" at the end of an episode. The producer liked it so much that it became the signature final line of each episode, as Sam finds himself in a new body.
Al's call-sign (pilot nickname) is "Bingo".
Sam leaped outside his life a total of four times. Two of the leaps (to 1945 and 1862) were explained. In "The Leap Back", Al and Sam traded places due to an accident, which allowed for leaping within Al's life. "The Leap Between the States" revealed that Sam's great-grandfather John had a very similar genetic profile and blood type. Two unexplained leaps before his life were "Play It Again, Seymour" (April 14, 1953) and "The Americanization of Machiko" (August 4, 1953), as the series finale revealed Sam's birth date as August 8, 1953. However, both were after he had been conceived (which would have been at the end of 1952), so he did technically exist at that point.
Sam leaps into August 8, 1955 twice ("The Color Of Truth" and "Trilogy, Part, 1"). This was also his second birthday.
In "Lee Harvey Oswald", Sam, as Oswald in 1959, has a run-in with a certain Marine named "Bellisario". Series creator Donald P. Bellisario did in fact serve alongside Lee Harvey Oswald in the Marines.
Donald P. Bellisario took the idea for the series from a scrapped premise for Galactica 1980, where the villain would have continued traveling through time after the first episode and the Galactica crew would have to prevent him from altering history for the worse. Which might make this series the only good thing that ever came out of Galactica 1980.