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 - chronological order
Directed by: Tomas Alfredson
Starring: Henrik Dahl, Kare Hedebrant, Lina Leandersson, Per Ragnar
Continuity mistake: When Oskar shows his Rubik's Cube to Eli and explains how it works, one side is all white except one square, which differs from being red vs. blue between shots.
More trivia for Let the Right One In