The Hippo Lady's voice changes from episode to episode. In some episodes she talks like Ed Bighead, in other episodes, she has a raspy, more feminine voice. (Actually she has both voices. Her normal voice is effeminate, but when she gets aggrieved - usually by Rocko inadvertently) she takes on her more manly voice and utters her catchphrase, "How dare you!"
When Heffer and Filburt ring Rocko's doorbell, the only doorbell button is to the right of Rocko's door. When Rocko answers it and thereafter, the only doorbell button is to the left of the door.