As a teacher who has used this films and others to illustrate Hamlet, I can tell you that the director took some liberties with the script and the staging.
Most obviously, about half the play is missing! The entire subplot concerning Fortinbras and his impending invasion is left out. As a result, there is no real return to order at the end of the play. Hamlet dies and that is it; this is uncharacteristic of Shakespeare who always restores order in Act V. In addition, several of the longer scenes are shaved down, particularly the "closet scene" in Act IV. Much of Hamlet's rambling dialogue is shaved to move the scene along more swiftly to appeal to the attention spans of modern movie-goers.
Next, some interpretations of the text were extended and even exaggerated. The subtle insinuation of the Oedipal complex between Hamlet and his mother is made into a literal "near-sex" scene in which he lays on top of her and she kisses him on the mouth. The graveyard scene is less of a scene of comic relief as it is in the text than it is a mere transition to the next scene in the film.
Of course directors make decisions that they believe will appeal to the widest possible audience. These changes are meant to change the text into a modern, visual experience.