During the film's production, Aurora contacted Wham-O, the manufacturers of Frisbee flying discs, with concerns about possible trademark infringements if the "Mrs. Frisby" name in O'Brien's original book was used in the movie. Wham-O rejected Aurora's request for waiver to use the same-sounding name to their "Frisbee", in the movie. Aurora informed Bluth & company that Mrs. Frisby's name would have to be altered. By then, the voice work had already been recorded for the film, so the name change to "Mrs. Brisby" necessitated a combination of re-recording some lines and, because John Carradine was unavailable for further recordings, careful sound editing had to be performed, taking the "B" sound of another word from Carradine's recorded lines, and replace the "F" sound with the "B" sound, altering the name from "Frisby" to "Brisby".