– The decision to put the WWE World Heavyweight Title on Seth Rollins at WrestleMania 31 was not a last minute decision but only a few people were aware of the plan.
Reigns was originally planned to win the title but Rollins found out he was winning it late in the show. He was also informed that after winning, he would have to take the flight to New York City for The Today Show and the back to California for RAW.
Rollins reportedly was informed of the last 45 seconds of the match and that he was winning the title by a WWE producer right at the start of the angle between The Rock and Ronda Rousey. It was then that Rollins, Reigns, Brock Lesnar and Paul Heyman went into a room with Michael “PS” Hayes to work out the new finish of the match. The rest of the match had already been mapped out by that time.
Source: Wrestling Observer Newsletter