Revealing mistake: Near the end of the film, the mayor, played by Jim Backus, is speaking to Elliot the dragon, who is invisible. The mayor has a cigar in his mouth and smashes it when he turns to greet Elliot. The scene is accomplished by having Backus turn and smash the cigar into a large pane of glass. However, the reflections on the glass are visible.
Character mistake: During the "Money by the Pound" song, towards the end, Doc sings, "Can't you hear that jingle jangle sound." Hoagie (Red Buttons) starts mouthing the "Can't" before he catches himself.
Answer: In the original film, the credits show his name as "Elliott" (with 2 t's). In the remake, his name is "Elliot" (with 1 t). So older memorabilia will have "Elliott". In the original film, Elliott was the dragon's given name, in a manner of speaking. In the remake, Pete names the dragon after the puppy from his favorite book which was called "Elliot Gets Lost". This is the only reason I can find for the spelling change.
Bishop73