Although Mel Blanc provided the voices for the Looney Tunes characters, they all sound askew. There was an editing blunder which resulted in his recordings being played at the wrong speed.
Originally, the movie included a sequence in which Drac, Frankie, and Wolfie followed Hauntleroy through a mirror, where they all magically transformed into live-action characters. This scene was omitted from the European video releases. This segment was later re-edited, padded with new material, titled "The Haunted Heist," and featured in reruns of the Groovie Goolies show.
The first time Warner Bros let another animation company use Looney Tunes characters.