Pete’s return undoes whatever happened to Ray and Toby, and now the trio scrounge clothes, arm themselves, and resume their temporal quest. However, two things now happen in the men’s room. First, they hear themselves entering, and hide in the last stall, narrowly avoiding interacting with themselves. Second, while they are arguing, a younger Pete enters, sees them arguing, and flees.
The first event is interesting for what might have happened: had Pete warned them against entering the ladies’, they would not have traveled to the post-apocalyptic future and would not be here now to warn themselves–an infinity loop. On the other hand, interference with the timing is itself problematic. We expect that the destination point is somehow determined by the moment of departure, that is, if you stay another minute you wind up elsewhen. Thus had Pete warned the threesome against entering the ladies’, they would have left the gents’ at a different moment, not half an hour before they entered but at some unpredictable other time.
That did not happen then; but it might have happened with the other encounter. While Pete has his back to the door and is threatening Toby and Ray, both of whom are oddly dressed wearing hoodies which help obscure their identities, the Pete who has been petering about through time enters behind him. He sees a man with a knife threatening two men in hoodies, and immediately exits.
Toby picks up on this, because Pete mentioned having seen them when they donned their clothes in the future; but of course, he didn’t in this history, because he did not see them until after they had doubled back and crossed paths with him there. That also means that on this particular entrance, he left the loo sooner than he would have done, that is, than he did in the original history. That in turn means that he changes his path through time, going to different times thereafter. Again we have the implausibility that one of these trips takes him to exactly the right moment to prevent Ray and Toby from returning to the ladies’–implausible because not only is that a very narrow target time in the history of the world, but he hits it coming along two different paths.
Or perhaps how long you stay in or when you leave is irrelevant to your point of arrival. After all, the trio pursue the other Pete as he flees the gents’, and wind up at the fan party where he apparently did not go. The juxtaposition of the seemingly capricious nature of the time travel against the seemingly established arrival points is one more oddity here, but since the film never attempts to explain why anything happens the way it does it is difficult to say when what happens is inconsistent with its own theories.