While Phineas and Ferb reenacted the Trojan War, They flew on laser-shooting chariots, and tied up the legs of the Trojan T-rex, causing it to colapse and explode.
At one point during the song when Phineas's side is launching water ballons at Buford's army, Buford very calmly steps out of the way of an approaching ballon in a similar way to a scene in this movie with an Orc General steping out of the way of a boulder.