Did You Know?
In the establishing shot for this story, there is only one tree in the Flynn-Fletchers' back yard. Later in the story, Phineas and Ferb are having a tree house fight with Candace and Stacy, using two separate trees. Finally, after their mobile tree houses leave then return back to the back yard, there is one tree in the yard just as they return, bringing the total up to three trees. See more
References Pimp My Ride