User blog comment:Jrsushilover7/Back to the Future!/@comment-5093389-20130501151555

Problem: Future Mabel has already created a paradox. By going back in time to warn the twins, she has given them a chance to undo Dipper's death and Gideon's takeover. If they succeed, they will have no reason to travel back in time, which means they won't stop Gideon, which Mabel will travel back in time to warn them, and they'll stop the disaster, so they'll have no reason to go back in time ect...

If Mabel traveled back in time after they saved the day to mack sure their past selves stopped Gideon, then it might work, but it's still shaky.

Also, they're going to have to hide Waddles pretty good or else Gideon will just find him. I hope the plot stays intact! Good luck!