Though all home video releases have since made it seem otherwise, The Undertaker's WrestleMania XXVII entrance was significant because it was the first time since returning as 'The Deadman' that he didn't utilise his signature theme on the 'Grandest Stage of Them All' (as he entered to Johnny Cash's 'Ain't No Grave' instead).
Visually, it was the exact same as the majority of his entrances at the time, save for thin fire-bursts spurting out of the cool dome-shaped staging, but the change of theme was an interesting one. It certainly worked from a character standpoint, given that he was taking the western aspect of his 'Last Outlaw' gimmick a lot more seriously than usual, and 'Ain't No Grave' always translated well on TV. However, it didn't quite fill the large arena in the same way that his triumphant theme would have.
Nonetheless, 'Taker and Johnny Cash were a great match.