User blog comment:Mobo85/Phineas and Ferb Feature Film Has Date with Destiny/@comment-1852035-20111014031313

The reason why the date was July 26, 2013 because Thor 2 was supposed to premiere on July but Disney decided to move it to November just for the Phineas and Ferb movie.

Speaking of Thor, any Avengers fans might read this the first official trailer was out a few days ago.