Rex is a minor character in the film, with no speaking lines and appearing mostly as a background character. He first appears in the church audience after the Were-Rabbit's rampage, listening with fear to Reverend Hedges, cowering when Victor Quartermaine points his gun at him and some other people and is supportive of Anti-Pesto being given a second chance at catching the creature. He later appears at the vegetable competition at Tottington Hall, where he joins the others in begging Mrs. Mulch to come back and cheers Anti-Pesto after they draw the Were-Rabbit away from the competition stand. The beast returns when he sees Lady Tottington in peril, however, and Rex flees in terror and is not seen again.