When Shae is hitting the mutant with an ax, she is having flashbacks of all the characters that were killed. However, the Jenny character is in there too and Jenny and Shae never met in the movie.
The movie takes place in Ireland but the van is left-hand drive
and drives on the right side of the road as if it's in North America.
A North American snowmobile can be seen in the woods. Ireland doesn't have the snow for these type of vehicles.
An Irish character refers to eating haggis, a Scottish dish.
Karen Douglas despite being a teacher in Celtic studies (pronounced 'keltic') uses the pronunciation with the soft-c or 's'-sound.
In addition to the "soft c" in "Celtic," they pronounce the word "Samhain" as "sam-HAYN..." when the actual pronunciation is not even the once widely-held (but incorrect) "SOW-ehn," but actually "SHAV-nah."