#3 The Montreal Screwjob
The most famous example of real-life issues being brought on screen, the Montreal Screwjob is still a sore spot all these years later.
If somehow you don't know, Bret Hart and Shawn Michaels were in a bitter feud, both on-screen and in real life.
Informing the company that he was to leave following Survivor Series, the plan was for the Hitman to successfully defend his WWF Championship against Michaels, and relinquish it the next night on RAW.
At some point though, Vince McMahon's mind changed, possibly because he feared Hart would join WCW as the champion, just as Alundra Blayze had appeared in WCW as the WWF Women's Champion three years prior.
Mid-match, Michaels locked in the Sharpshooter, and the bell was rung. Michaels became champion, Hart was screwed, and wrestling was never the same.