Right before Cat begins singing the Abraham Lincoln song, Dog doesn't have his costume on as he reminds Cat of his lines but towards the end of the song, Dog has his costume on.
After Cat gets bit on the nose by the little dalmatian, when Dog asks why their house is burning down, Cat's nose is bright red, a second later, it's his normal nose color.
(Cat gets the role of Hezekiah the donkey)
Dog: And look Cat, you have a line.
Cat: (reading the script) He-Hah.
Winslow: Buckle in, Dog. It's going to be a bumpy ride.