Voyager from the Unknown (1984)

It is 1984. Jeffrey Jones is an 11-year-old orphan entrusted to his uncle and aunt. One evening, Phineas Bogg crashes through his bedroom window. As the young boy's dog rushes to the intruder, he bites into the book in Bogg's hand. In the ensuing panic, while trying to snatch the book from the fangs of the animal, Jeffrey swings out the window. Bogg jumps into the void to catch him and both are projected into time. Phineas Bogg is part of a group called the "Travellers". As they try to return Jeffrey to his own time, they encounter famous people from the past — while trying not to alter the path of history.

Unfortunately the movie Voyager from the Unknown is not yet available on HBO Max.