The family was named Kerrigan so the filmmakers could borrow trucks from an actual tow-truck company, Kerrigan's Towing.
As of 2018 the house used to film "The Castle" was set to be demolished on more than one occasion but something stopped both council and demolition crews, mainly due to backlash to leave the house alone, and that it should be left alone because the movie is an Aussie classic.
Originally made to raise money for the later Australian film "The Dish".
The shooting schedule was cut from from 20 to 11 days - the number of days the filmmakers could afford to feed the cast and crew.
The BMW Dennis is driving belonged to Eddie Maguire, who lent it to the film production for that scene.