User blog comment:Poptropica411/Phineas plus Isabella equals Phineas and Ferb: Across the Second Dimension in Fabulous 2D?/@comment-74.98.161.253-20110305144444/@comment-1647442-20110319192431

Plus, it's called "Phineas and Ferb Across the blah blah blah in Fabulous 2D"

If it was in 3D it would say so :P

Also, unrelated, but I seem to recall Swampy mentioning something about 2D glasses at Comic-Con for this movie...