* In Claudius first speech to Hamlet about his grief over his dead father, he say this:
-> Why should we in our peevish opposition \\
Take it to heart? Fie! 'tis a fault to heaven, \\
A fault against the dead, a fault to nature, \\
To reason most absurd: whose common theme \\
Is death of fathers, and who still hath cried, \\
'''From the first corse''' till he that died to-day, \\
'This must be so.' We pray you, throw to earth \\
This unprevailing woe, and think of us \\
As of a father...
* Who was that first corpse he talked about there? Abel. ''A man who was killed by his own brother!''
* If you subscribe to the idea that Gertrude was a knowing participant in her late husband's murder, the causes of death in the last scene make perfect sense: The two gallant sons avenging a murdered father's death is killed by the sword in honest combat while the villainous conspirators are killed by poisoned drink, often called a coward's weapon.
* Although I'd read Hamlet in High School, and knew that Gertrude's line: "Methinks the lady doth protest too much" came from the scene of her watching (essentially) an {{Expy}} of her marriage to Claudius, it wasn't until after college that I realized the significance of Hamlet's line leading up to that quote. He's basically asking her if she's enjoying the play, but the exact words he uses are: "How like you this play, Mother?". With a different inflection, this could be a statement. "How LIKE YOU this play, Mother". Brilliant.
* Another piece of wordplay-related brilliance in Hamlet: Claudius' line, "My offense is rank; it stinks to heaven". It struck me at a literal fridge how layered and complex this line is, and how elegant a fusion of the tragic and the comic. Claudius' offense is 'rank' both in the sense of an unearned position (his ''rank'' as king) and in the sense that his offense is figuratively smelly and repulsive. It "stinks to heaven" both in the sense of a rising stench, and also in the sense of being repulsive to the heavens, an affront to the sacred.
* When Claudius prays for forgiveness in Act III, he says something to the effect of his crime being subject to the "most primal curse." But, of course, Claudius comes out of a very Christian background. What anecdote in Judeo-Christian teachings talks about a brother killing a brother?

* After they finish depicting an all-too-accurate version of the murder of Hamlet's father, what happens to the Players? Claudius likely has them interrogated and imprisoned to determine the source of their information and to prevent it from spreading.

* It always astounded me how vicious Hamlet became toward Claudius. Old Hamlet only told Young Hamlet to avenge his death. Nothing about making sure he's punished, just kill him. Right after the players leave, Hamlet is presented with a perfect chance to kill his uncle, but he doesn't. Why? Because his uncle is praying, and he doesn't want him to go to heaven. He doesn't just want to fulfill his father's wishes, he wants to send Claudius to Hell.
** Back in the Ghost's speech he alludes to the fact that, since he was killed suddenly, he was not allowed to repent or have his last rites and thus was never cleansed of his sins, leaving him trapped in purgatory. If Hamlet had killed Claudius while he was praying, he would be sending Claudius to Heaven, since his soul would be cleansed of his sins. The whole speech Hamlet gives when he is about to kill Claudius ends with Hamlet deciding not to kill Claudius until he is drunk, partying, and full of sin, so that Claudius will share the same fate as Old Hamlet. He doesn't just want to "send Claudius to Hell", he wants to make sure he has proper revenge. Of course, since not a single character (except maybe Laertes) got a chance to pray or repent in their last moments, they're probably all trapped in purgatory now...