Subterfuge and Conspiracy.
One of the main themes of the film is subterfuge. At certain moments in the plot, everyone seems to be plotting against everyone else; Claudius is constantly plotting and has only become King because of his murder plot against his brother. When he realizes that Hamlet knows about the murder, he plots against him as well. He co-opts Hamlet's former friends to help facilitate Hamlet's execution.
Laertes is also keen to enter into the subterfuge with Claudius because he is enraged by his father's murder, and also by the fact that his sister has gone mad. He does, though, realize that this subterfuge was wrong and apologizes for it as he lies dying. Hamlet is also engaging in subterfuge, conspiring with Horatio, in an effort to avenge his father's death and kill Claudius. This conspiracy is more successful in some ways although it is not enough to protect Hamlet from being murdered himself.
In the background, there is the Prince of Norway, who is engaging in subterfuge, by pretending to be just passing through Denmark on his way to Poland, when in fact he is tactically making sure that they are allowed un-challenged entry into the neighboring country without having the Danes repel their invasion.
Face Value
Hamlet takes nothing at face value; in fact, the film goes to great lengths to disprove the value or veracity of face value.. He is anxious to avenge his father's death but he is not entirely sure that the ghost really is that of his father, or whether the information the ghost is giving is actually true. Is there even a ghost at all? Perhaps it is Hamlet creating the ghost because he is so distressed about his father's death. Can he take the ghost at face value or do the claims he makes require further investigation?
Claudius is convinced that he can tell the state of Hamlet's mental health at face value. This is patently untrue because Hamlet is pretending to be mad when in fact he is not. Claudius has completely accepted that he is insane, but is trying to discern why this might be and believes that he can tell whether it is out of lovesickness, or another cause entirely.
Death and the Afterlife
The film revolves around death; murder, grief, suicide - all of these are cause for great pondering and philosophizing by Hamlet and the other characters. Hamlet does not know what he believes about the afterlife, which is why he finds the appearance of the ghost so confusing and mystifying. He is reminded about those who have already passed when he finds Yorick's skull in the grave that is being re-dug for Ophelia.
Hamlet has many questions about the afterlife; he does not want to kill Claudius whilst he is praying because that would enable Claudius to go straight to Heaven, which Hamlet does not think he deserves to do, whereas his own father, who is not at peace, is still in purgatory.
The Tragedy of Love
Ophelia and Hamlet are in love with each other but this does not seem to matter to Claudius or Ophelia's family. Neither her father nor her brother want her to have a relationship with Hamlet and order her to return his love tokens. She is so distraught about the ending of their love that she is driven insane. Similarly, Hamlet risks danger and possible murder when he reveals his hiding place at the funeral procession; he comes out from hiding when he realizes that it is Ophelia who is being buried, declaring his undying love for her.
