Had the same thing happen in 5v5 normals on SR, at around 2:30AM 12/28/14, it was lunacy! We just grouped mid and lucked out. CSing was impossible, team fighting was hilarious. Everything was gliding all over the place, minions would die but their undead bodies would continue to fight on without dealing damage. One of the weirdest games I've ever played. Started out with a bit of a delay here and there before the minion spawn, by the time laning started things were crazy.
I spectated a game right after, to see if it was just us, because I didn't see any alerts in the upper left of the client, the game played out just fine. Went to view my opponents' profiles, they didn't have prevented losses. Glad it was just normals, I'd hate for them to lose points based on such a game breaking glitch.
Match history for that crazy game: http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/1679386608/206241326?tab=overview
note that the game ended at a little over 20 minutes and the highest CS was 42... obviously something went wrong.