It is hard to tell if the Oscars are rigged or not but it is obvious that others most likely do not know who will win and who will lose. This is because some of the announcers of the winners have been mistaken and call out the wrong winner. So, obviously they do not know who is going to win or they wouldn’t have gotten the winner wrong.
Now there is a chance that the Oscars are rigged and choose the people they want to win. It would be difficult to prove this, but there is a chance of it. A statistician would be able to look at the winners and losers during the years past for the Oscars and see if there is a pattern.