* CreatorBacklash: Russell Harvey, heir to the Harvey Comics legacy, thoroughly hated this film and how it forced child-unfriendly humor and an overly-dark, completely pointless backstory into something so beloved for its innocence. He also expressed disappointment in Steven Spielberg, whom he felt [[TheyWastedAPerfectlyGoodPlot wasted the perfect opportunity]] for a legitimately heartfelt adaptation.
* CutSong: "Lucky Enough to Be a Ghost".
* DawsonCasting: Mostly averted; all of the teenagers are played by actors between the ages of 13 and 15; Casper's voice actor is 14. The trope is only played straight near the end of the movie, with [[spoiler:a 17-year-old actor portraying Casper, a 12-year-old, during his temporary restoration to life.]]
* DeletedScene: In the mirror morph scene, Dr. Harvey was originally also going to get changed into Steven Spielberg. The cameo was actually filmed, but cut from the film for pacing reasons. Spielberg was actually very happy about this, feeling that he's not much of an actor and was quite nervous in front of the camera.
** There's also a musical number by the Trio called ''Lucky Enough to Be a Ghost'', which was cut because the special effects needed to create it would've blown the movie's budget right out of the water. It can still be found on the DVD in two versions; the first which includes plastic models of the Trio that would've been used as a guide for the animators, and then a second version of Dr. Harvey on his own which would've been used in the film had they not cut it.
* MoneyDearBoy: The only explanation for the celebrity cameos. Or the long-term presence of Eric Idle.
** Clint Eastwood and Mel Gibson's cameos were technically done out of a favor to Steven Spielberg, though this probably played a part in it too.
* OrphanedReference: In the finished film, Kat mentions that her dad "hit the ceiling" when she told him about the party. This is a reference to the end of the deleted ''Lucky Enough to Be a Ghost'' scene.
* TheOtherDarrin: When Casper does an [[TheAhnold Ahnold]] impression, he's voiced by Creator/JessHarnell.
* WhatCouldHaveBeen: A sequel was in the works, though Amblin eventually shelved it, feeling that audience interest wasn't high enough for a follow-up.