On Aug. 21, 2020, Mike Isaac and Sheera Frankel of the New York Times reported that Facebook is developing contingency plans just in case Donald Trump "wrongly claim[s] on the site that he won" contrary to the actual election results should they be against him. Facebook is also weighing how it should deal with Trump's attempts to delegitimize the actual election results by "by declaring that the Postal Service lost mail-in ballots or that other groups meddled with the vote." The source are "people with knowledge of Facebook's plans. Facebook is even considering creating a "kill switch" to remove political ads that contain false election results.
Google is also discussing contingency plans for the U.S. elections, but didn't reveal further details.
It's not hard to envision another nightmare Bush v. Gore scenario, in which the result of the presidential election is contested. Trump has already attacked mail-in voting. According to the NYT, in part due to the pandemic, 9 states have mailed ballots to all voters, while 34 other states allow voters to elect mail-in voting for any reason and 7 states allow mail-in voting for certain reasons. Prof. Ned Foley has highlighted one reason this year's election may result in a contested outcome and litigation: mail-in ballots typically result in a "blue shift" with more ballots for Democrats than Republicans in past elections from mail-in ballots for reasons that are not entirely clear. Thus, in close races, the "blue shift" might flip a state from Republican to Democrat when the mail-in votes are counted, giving rise to unsubstantiaed claims of foul play. For more about this scenario, read this Atlantic article.