None of the men's MITB Ladder Match competitors in the match were aware of Lesnar's return ahead of time. PWInsider reports that the competitors were told that there would be a spot at the end of the match where Ali would be standing on top of the ladder, and would be tipped over. They were not told who would be coming out to do the spot.
There was also talk throughout the day that Ali would be winning the match, another sign that WWE took extreme measures to keep Lesnar's return a secret.
Lesnar was never seen on Sunday until he came to the Gorilla Position towards the end of the main event. There had been rumors going around backstage on Sunday, but no one could confirm he was there.