"When the World Ends" was originally supposed to be the single, but after 9/11 it was thought that the dark title would not be appropriate.

The wager of the day on the site: "Will the World End on 6-6-06?"

"Till the World Ends" leaked online on March 3, 2011, and was released the following day.

"Till the World Ends" was made available on iTunes the same day, several days earlier than originally planned.

"Till the World Ends" stayed for sixteen weeks on the chart.

"Till the World Ends" is nearly the 40th music video Spears made in her career.

The single cover for "Till The World Ends" is incorrect.

There are two versions of "Till the World Ends".

The final section of the last level is titled "The Way the World Ends".

The album's first single, "Watch the World End", was released to country radio on May 13, 2013.