Faithless electors
For everyone who is hoping, praying, sacrificing animals, or otherwise trying to wish for an electoral uprising, please remember this...when Congress meets on January 6, 2017 to count the electoral votes, they can challenge each and every vote.
It's time consuming, and they have to have written challenges from both a House member and a Senator for each challenge, but it's an absolutely legal response to faithless electors. And if anyone thinks that the Republican House and the Republican Senate are going to let a Republican Presidency slip through their fingers by allowing faithless electors, I would submit that you haven't been paying attention. They can toss the votes, throw the Presidential election to the House, the Vice Presidential election to the Senate, Trump wins anyway, Pence wins anyway, and red state Democratic Senators up for election in 2018 are put into an impossible situation.
Given the past year in politics, I would never say never, but I can't see any way possible for faithless electors to upend this election.