Complex sentence: The "Mrs. Frisby" name in the novel had to be changed to "Mrs. Brisby" during production due to trademark concerns with Frisbee discs.
Split into simpler sentences: The "Mrs. Frisby" name in the novel had to be changed to "Mrs. Brisby" during production because of a trademark conflict. The name is Brisby in the film to avoid trademark concerns with Frisbee discs.