Real wolves were used in the scene where they chase Dave down the street. However, they were overwhelmingly tame and affectionate creatures so track points were painted on their faces so that the CG artists could animate a more scary face onto them.
One of the people that Horvath summons is Abigail Williams. At age 12, Williams was the first person to make the accusation of witchcraft in 1692 Salem, Massachusetts. This led to the Salem witch trials and the deaths of at least 20 people. There is no definite evidence of what happened to Williams after the trials ended.
The 1935 Rolls Royce Phantom that was used in the film is a one of a kind and actually belongs to Nicolas Cage. The filmmakers were trying to find a really cool classic car and Cage offered it as an option to use.
Although the film, as its title shows, is ultimately based on Johann Wolfgang von Goethe's famous German poem "Der Zauberlehrling" from 1797 (which inspired the piece of music by Paul Dukas from 1897, also briefly heard here, which in turn was used in the adaptation in "Fantasia" starring Mickey Mouse), the German version completely missed this connection, translating the title instead as "Duell der Zauberer" (Duel of the Sorcerers).
During filming, an accident occurred when a filming of car chase sequence went awry. The filming accident, which caused two bystanders to suffer minor injuries, occurred Monday, May 4, shortly before 1 A.M. at the Sbarro at 47th Street and Seventh Avenue Street when one of the cars used in the chase sequence suddenly careened into a pizza parlor.