Barbary-Coast Bunny

The winning hand that Bugs has in the climactic poker game with Nasty Canasta that he describes as a "Two pair. A pair of ones and another pair of ones" is called a Quad of Aces, the highest value of a four-of-a-kind that can be topped only by a straight flush or a royal flush.

Early in the cartoon, Bugs is tunneling his way to San Francisco when he hits his head on a rock. As he lifts and rolls it out of his way, the background is visible through it, and it becomes apparent that only the rock's outline has been painted. The error is only noticeable for a few frames, when the rock overlaps a part of the background that isn't the same green as the surrounding grass. It's likely it was meant to be filled in with the same green as the grass; because it looks filled in when it's over that area. This is probably the reason for the error.