An Irish music competition such as the one portrayed in the film is called a "fleadh" (pronounced like "flahhh"). However, nobody uses this word in the movie.
The film is supposedly set in the early 60's when the Beatles were a beat band. Yet we see an English car with an H registration - not issued until August 1969. Alex and Teddy also mention Kevin Keegan signing for Liverpool. This did not happen until 1971.
At various times throughout the film (notably in the pub and during the ceilidh band competition) when we see Anne (Andrea Corr) playing fiddle, her bow is moving but her fingers are not.