The original plan was to have The Rock pass the torch to Cena, but only days before the actual event, the WWE writers decided to make The Rock win in the main event because John Cena winning seemed too predictable. Most writers still thought Cena was supposed to win until they saw the match live.
The Undertaker vs Triple H was only the second Hell in a Cell match in WrestleMania history, the other was the Undertaker vs Big Boss Man at WrestleMania 15 and the third overall WrestleMania match to be held in a steel cage type structure the first being Hulk Hogan vs King Kong Bundy in a steel cage at WrestleMania 2 however the Hogan-Bundy match at WrestleMania 2 remains the only steel cage match in WrestleMania history
The Rock/John Cena match was the first time a WrestleMania main event was announced and promoted a full year in advance.
A match was planned between Big Show and Shaquille O'Neal. O'Neal promoted the match for months in interviews. But the match did not happen for unknown reasons.
The third WrestleMania match between Undertaker and Triple H, having fought at the same event the previous year and at 2001's WrestleMania X-Seven