As Bugs digs "his" grave, he shovels the dirt to his left, but in the next shot, as he buries Elmer he shovels from the right.
While cradling the "dying" Bugs Bunny the elderly Elmer Fudd's mustache disappears for a few frames.
Bugs digs his own grave, then tricks Elmer into switching places, so that Elmer is in the grave and Bugs by the grave side. But when Elmer is initially in the grave, it is so shallow that his hat is above the ground surface. Moments later, when the camera vantage point is from the bottom of the grave, Elmer is in a deep grave, so deep that his hat is well below the surface of the ground.
Bing Crosby passed away in 1977 at age 74. Smell-o-Vision didn't actually replace television. It shows up now and then on certain events and programs.
As Old Bugs runs away from Elmer, a futuristic building in the background keeps disappearing repeatedly just as it reaches the edge of the frame.