In the commentary, they said that they want to point out the "surprises" but they didn't want to explain them because they didn't want to ruin them. They pointed out Nibbler's shadow under the desk (well, they said "there's one" but they didn't actually point out the shadow). Then they said it again when what seems to be when Nixon said "get those bums". Anybody know what that is all about?
And kudos to the Futurama crew. Apparently they knew -exactly- where the series was going, as they seem to have all the gags planned out at the beginning and then go back to it later (like Nibbler's shadow under the desk). It's kindda like Back to the Future! :o