The 13 Ghosts of Scooby-Doo (1985) had Daphne take the role of leader (with a new purple outfit) and had the gang use a red van instead of the usual Mystery Machine, both of which happen in this feature.
Shaggy's voice actor Matthew Lillard was previously in a movie called Thir13en Ghosts (2001), which got him noticed to play Shaggy in Scooby-Doo (2002) and Scooby-Doo 2: Monsters Unleashed (2004), and later as the new voice for the animated version of the character since 2010, after Shaggy's original voice actor Casey Kasem stepped down in 2009.
Vincent Van Ghoul is modeled after 20th-century horror icon Vincent Price, who originated the character's voice in The 13 Ghosts of Scooby-Doo (1985). Vincent's past partner Mortifer has some qualities in common with Peter Lorre, who costarred with Price in a number of films.
The clothes that Daphne uses in a large part of the film are based on her 1980s clothes with slight modifications to make her look a bit modern.