WMG: Mamma Mia!

Everybody can teleport
There's a lot of scenes in which a character moves between takes way more than they could, like when Rosie falls from the roof and Bill catches her, or Pepper getting in the bench at the beginning of "Does your mother now", or nearly all "Lay all your love on me". The answer? Everyone has teleportation powers, which aren't discussed because they're just mundane for the characters.
  • They only work while they're on the island. That's why Rosie, Tanya and the three fathers still have to arrive in boat.

Harry is secretly a spy.
Namely, Harry "Galahad" Hart from Kingsman: The Secret Service. Two characters, both named Harry, both played by Colin Firth? Coincidence? I think not.