With this bold move, Zim wins. Cue the cackling! But he rips a hole in the space-time continuum in the process, endangering the Earth to be flung into a void of colliding infinite alternate realities. That's the "Florpus" of tit all, and neither Zim nor Dib can save the Earth from it alone.
The funny thing about the Florpus is that it only shows up more than halfway through the movie and it's also not referenced at all before it does. The Florpus feels almost incidental to the larger conflict of the movie -- the mirrored antagonism of Zim and Dib. The film may be titled Invader Zim: Enter the Florpus, but the title screen that precedes Invader Zim reads Dib Membrane vs., after all.
"From the moment my mission began on this horrible planet, you've been there, haunting my every move like a squak in my schmoopsquizz," Zim reminds us after the opening credits have barely rolled. These two despise each other, and yet they can't stay apart.
Neither the Tallest nor Professor Membrane model very good behavior for Zim or Dib. Despite Zim's best efforts to impress them as a conqueror of worlds, the Tallest abandon, gaslight, and shun Zim at every opportunity -- seemingly for no reason other than the fact that they find him annoying. And despite Dib's best efforts to prove to his science-minded workaholic dad that his alien-hunting efforts aren't a make-believe game, Professor Membrane refuses to acknowledge them -- even as he careens through myriad realities, all with an impressively distinct animation style, he shouts about how none of what's happening is real -- but is perfectly fine with his 12-year-old son wasting away unshowered in a dark room for months.