The first part of the end credits shows clips from this movie and the original ''Dumb and Dumber''.
SPOILER: After the end credits, Harry and Lloyd are riding in the Zamboni, complaining that they got the wrong milkshakes (when in fact, they are drinking each others' milkshakes). They toss them backwards for the shakes to hit the truck of their old nemesis Sea Bass. He follows them as a text comes up for a faux fourth installment, "Dumb and Dumber For", coming in the summer of 2034, followed by a camouflaged Captain Lippencott walking out of the text.