Thunder / Dylan (voice)
Maggie (voice)
Jack / Carlo (voice)
Mr. Lawrence (voice)
Daniel (voice)
Chihuahua (voice)
Carla (voice)
Nurse Baxter (voice)
Izzy (voice)
Mark Matthews (voice)
Mike Matthews (voice)
Hospital children (voice)
Hospital children (voice)
Hospital children (voice)
Hospital children (voice)
Reggie (voice)
Audrey (voice)
Lasondra (voice)
Mr. Eames (voice)
Mrs. Eames (voice)
Old Lady (voice)
Cat sounds (archive footage; uncredited)