When Elmer is stabbing Bugs' hole with his spear, there are rabbit tracks around the hole. But when Elmer says "I'm going to kill the wabbit!" the rabbit tracks have disappeared.
When Elmer Fudd shouts "Smog!" whilst summoning the various forces of nature, he is voiced by Mel Blanc, not Arthur Q. Bryan. Blanc was chosen to do this line as his scream was considered to be better than Bryan's.