In one scene, Mike wakes up and begins describing his "dream" of being in high school again only to find his daughter, Maggie, caring for him. This is an homage to the counterpart scene in Back to the Future (1985) in which Marty McFly wakes up and finds his teen-aged mother caring for him.
Toward the end of filming Zac Efron had appendicitis. It started out as a stomach ache but he had it checked out that night after filming and he had surgery that same night.
When back in 1989, Ned runs in late for the team picture wearing wizard robes and referencing a hippogriff, it may appear to be nod to Harry Potter (which was not published until 1997, and 1998 in America). However, the myth of hippogriffs is not a Harry Potter original, having been around for hundreds of years. Ned also makes reference to being "Dungeon Master", making it obvious he was playing Dungeons and Dragons, which has been around since the 1970s (hippogriffs included).
When Mike/Mark is shooting free-throws before the second big game there are seven balls on the rack including one on the top tier, after he talks to the coach there are only five with none on the rack and there hasn't been time or the sound of another shot.
As the title suggests, 17Again is a film about 37-year old Mike O'Donnell (Matthew Perry) who, dissatisfied with his life to date, suddenly finds himself 17 again with a chance to relive the life he lost by marrying his pregnant high school sweetheart Scarlet (Allison Miller). Mike, now going by the name Mark (Zac Efron), goes back to his old high school where he encounters his own daughter Maggie (Michelle Trachtenberg) and son Alex (Sterling Knight) and comes to know his 37-year old wife Scarlett (Leslie Mann) in a renewed light.
Q
Is "17 Again" based on a book?
A
No. 17 Again is based on a screenplay by American screenwriter Jason Filardi.
Q
Is this a remake of "Seventeen Again"?
A
No. The titles are similar, 17 Again and Seventeen Again (2000), but the story lines are not the same.