Revealing mistake: When Eli's guardian is disposing of the body of the man she killed in the underpass, we can see that the 'body' is a very poor quality dummy, the hands especially are very plastic-looking.
Let the Right One In (2008)
1 revealing mistake
Directed by: Tomas Alfredson
Starring: Henrik Dahl, Kare Hedebrant, Lina Leandersson, Per Ragnar
Other mistake: When Oskar finds the solved Rubik's Cube it cuts to a shot of Eli sleeping, wearing a large shirt/dress. However, this shirt/dress is the same one that she takes from Oskar's mother's closet later on in the movie and therefore, she wouldn't have it yet.
More trivia for Let the Right One In