Original series star Scott Bakula declined to return for this sequel, despite lobbying for a continuation to the original series for more than 20 years. Fans even speculated that Ben Song was actually tracking Sam Beckett (Bakula's character) through time to rescue him after the conclusion of the original series, which ended up not being true. Later, in interviews both Bakula and the producers of this show have admitted that the original pilot script for the reboot featured a cameo by Sam Beckett but disclose what his role was. However Bakula backed out and refused to reprise the role as either a supporting or recurring character, without the presence of Dean Stockwell who died in 2021. The producers have since said they have an "open door" policy with Bakula, and that he would be allowed to appear in the show at any time should he change his mind.
This series is a revival/continuation of the original Quantum Leap (1989) TV series. It makes several references to the fact that Dr. Sam Beckett is still trapped in time. It also acknowledges that Admiral Al Calavicci has died, as actor Dean Stockwell had passed away on November 7, 2021.
The premise of the Quantum Leap revival/continuation would have been entirely different if it wasn't for NBC deciding to cancel the original Quantum Leap (1989) at the eleventh hour. They replaced the last scene of the original show that was supposed to set up a sixth season with a simple title card telling viewers that Sam never went home. This was in line with how the original ending was shot but it includes a scene where Al declares he will go rescue Sam. Because of the abrupt cancellation, the studio kept the framework of the originally intended ending; the problem is they didn't think through the implications of this ending, which sees Sam's wife widowed. They didn't even spell Sam's last name right.
Despite being set in the same continuity of the original series, this revival/sequel series ignores several key rules of time travel as established in Quantum Leap (1989), such as the "waiting room" where whoever Dr. Sam Beckett had leapt into would be held until his mission was completed. Unlike the original series, they never say what happens to the person during the time Dr. Ben Song leaps into their body and does what he's supposed to do in order to leap again. Furthermore, in the original show Al had to act as Sam's holographic guide because Ziggy used brain cells from both men to create the cross-time link--their minds were literally joined and other members of Project Quantum leap couldn't use the imaging chamber, as Sam wouldn't be able to interact with them, where as in the new show anyone can use the imaging chamber. This new show also eliminates the character of Ziggy. Though still the computer that controls the quantum accelerator, Ziggy was originally portrayed as having a voice and personality. In the original series, Sam physically replaced the person he leapt into and only appears as the person to others - so, for example when he fathers a child it is genetically his; but in the new series it is only his consciousness that replaces the person leapt into, but it's their body. This is why no waiting room is needed. Where Ben's body is is never defined.