The New Japan Philharmonic gave the score a "luxurious sound" that was impressive given the limited resources available. The sound effects were not from a library, and were instead created using Foley, with various real world objects around Los Angeles being used in the score, such as objects in antique stores. This technique was used because Rees wanted to create new characters with new sounds. The sound mixers, including former Disney studio mixer Shawn Murphy who recorded the score, asked how they would do their job due to the film being animated, and Rees explained that they should mix it like any other film, instead of thinking of it like it were a cartoon.