A couple times Foghorn Leghorn's brown head feathers turn white.
The snow making machine is significantly smaller in size when the coyote kicks it and throws it off the cliff compared to how big it was when it was first introduced.
For most of the Christmas Carol segment Yosemite Sam has a full head of hair, however when he runs towards Bugs, Elmer, Foghorn, and Pepe he is bald.
In the Roadrunner sequence when Wiley gets tied up to his rocking horse, the rocking horse lands on some railroad tracks and slides up to a road crossing. Here, he comes to a standstill before the road. But in the next sequence, Wiley (still on the railroad tracks) is now in the middle of the road.
There were five snowdrifts created by the machine. The first, second, and fourth were exactly the same - just re-used.