The original screenplay written by Janice Fischer and James Jeremias was originally about a bunch of "Goonie-type 5th-6th grade kid vampires", with the Frog Brothers being "chubby 8 year old cub scouts", and Star being a boy instead of a love interest. Joel Schumacher hated that idea and told the producers he would only sign on if he could change them to teenagers, as he thought it would be much sexier and more interesting.
Kiefer Sutherland was only meant to wear the black gloves he wears as David when riding the motorbike. However, while messing around on the bike behind-the-scenes, he fell off, breaking his arm so he had to wear the gloves through the whole movie to cover his cast.
Though almost all of Kelly Jo Minter's scenes are deleted from the film, and the only true appearance she makes is over Lucy's shoulder in the video store, she still received billing the film's opening credits. Her scenes can be viewed in the 2004 Lost Boys DVD special features.
When Max first arrives at Sam, Lucy and Michael's house for dinner he does not enter until invited in by Michael. This echoes many vampire films in that, according to vampire myths, vampires must be invited in before they can enter someone's home.
In the opening sequence there is a random crowd shot that includes an older man in the distance with thick glasses wearing a Gothic looking hooded black robe. While his appearance is in line with the "spooky" factor of the film, he is in fact a semi-nomadic Christian.
Both of the two 1987 movies about a "family" of attractive vampires who lure a young man and make him into a half-vampire before he is eventually "cured" (Near Dark and The Lost Boys) feature a son of Jason Miller in their casts: Joshua John Miller is in Near Dark, and his half-brother Jason Patric is in The Lost Boys.
The second time Sam visits the comic shop two men can be seen playing pinball. The guy with the facial hair is Joe Ferrara who actually owned the comic shop Atlantis fantasy world. The comic shop has now moved location but is still owed by Joe.
This was Corey Haim and Corey Feldman's first film together, which marked the start of a popular 80s trend "The Two Corey's" in which Corey Feldman and Corey Haim starred together in a number of teenage films.
The trivia items below may give away important plot points.
David' (Kiefer Sutherland) is impaled on a pair of antlers and doesn't disintegrate like the other vampires. Despite what Max later says, he is not really dead. This was intended to be picked up in the sequel, "The Lost Girls", which was scripted but never made. In the Wildstorm comic's mini-series "The Lost Boys: Reign of the Frogs" (2008) - which helps bridge the 20-year gap between films - it's implied that 'David' not only survived the impaling but went on to create 'Shane' the head vampire in Lost Boys: The Tribe.
The movie didn't originally end on a joke. After the scene with Grampa at the refrigerator, it was supposed to cut to the surviving Lost Boys regrouping in the sunken hotel. The last shot was of a mural on the wall, made in the early 1900s, with Max in it - looking exactly the same as he did today. All of this appeared in an early draft of the script, but ultimately was never filmed.
In the cave of the Lost Boys you can see a poster of Jim Morrison who recorded the original version of "People are Strange" with The Doors. And when Star and Laddie are being carried into Sam's room, you can see a poster of Echo & the Bunnymen who recorded the version used in the movie.