A couple of other little hidden goodies in this:
'Pop' the iceberg: If you shoot the iceberg near the top right hand corner center (kinda feel around for it) you'll put a hole in the iceberg and it will begin to sink. Any and all penguins jump off it screaming.
Bird poop: In the intro screen that offers its advertisers, help, and start game, you'll notice a seagull flying over head click on the bird and drop some whitewash in the eyes of the elves, those little bastards.