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.
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.
The Chinatown sequence took 5 months to plan. Half a ton of confetti was used in this sequence.
The idea for the film was largely Nicolas Cage's as he wanted to explore a mystic world with a magical character.
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.