When Bart and Lisa go down the laundry chute, Lisa removes Bart's shoes and socks and throws his socks down the chute to get the puppies to go down and escape Mr. Burns. However, when Mr. Burns points his gun at Bart and Lisa after deciding he can't kill the puppies in the next scene, Bart's shoes are back on.
During the 'meal scene' when the turkey starts to move, we can see that it has hardly been touched, making the subsequent congratulations look overzealous.
Despite it being repeatedly stated that there are 25 greyhound puppies, when the camera pans across them eating from their respective bowls, 26 greyhounds can be seen.