I actually loved this movie, even after seeing the show on Broadway, but it is also easy to make fun of.
If you're easily offended by adult language, don't click this link.
If a few f words don't bother you, I thought this was hilarious.
http://www.the-editing-room.com/mammamia.html
There's a section about the scene on the boat and even though it's making fun of the movie, it still gives an idea of what each of the characters were talking about. That scene actually reminded me of Threes Company, where almost all the humor came from misunderstanding and taking conversations in the wrong context.
COLIN FIRTH
I will now engage you in one-sided misunderstood banter wherein I explain that I might be Amanda Seyfrieds father, but you infer Im a homosexual. This is supposed to be hilarious, except at the end you find out Im gay anyway, so this makes no sense.
STELLAN SKARSGARD
Oi! And I will explain to you that I think Im Amandas father, but no one will ever have a clue just what you infer from me, and its never explained again. You might think Im talking about *** Julie Walters or Meryl or my 20 year old possible daughter with huge tracts of land, or possibly that Im just expressing how much I enjoy Vegemite.