“I’ve got to go back and help,” says Cable, and the audience asks: Help with what?
I mean, the way I understand the current scenario, Agent Cable has completed her primary mission. She’s trying to prevent a magic spell from falling into the wicked hands of a sinister wizard, and the spell is written down in a little red leather notebook, which is the only place to keep anything. Cable currently has possession of the notebook, and the bad guys are busy having stupid boat fights with a big green monster, so this would be an opportune time for Cable to start looking around for some car keys. Cable wins, bad guys lose. End of movie.