The part where Guildenstern and his voice echoes and everyone just looking around in confusion when they hear the echo, Rosencrantz and Guildenstern especially when they look around, as if to say, "Did I/he just do that?" One example being this piece of dialogue:
Guildenstern: You know what to do. Rosencrantz: What? Guildenstern: Are you stupid? Rosencrantz: Pardon? Guildenstern: Are you deaf? Rosencrantz: Did you speak? Guildenstern:(realizing what he's doing) Not now. Rosencrantz: Statement. Guildenstern:NOT NOW!(echo and he and Rosencrantz both look around, as do all the players)
A brilliant little moment poking fun at the increasingly philosophical story:
Rosencrantz and Guildenstern introduce themselves to the Players...or, try to, anyway.
Rosencrantz: My name is Guildenstern, and this is Rosencrantz. (Guildenstern whispers in his ear) I'm sorry; his name's Guildenstern, and I'm Rosencrantz.
Guildenstern's long pause before telling Rosencrantz, "... I think I'm going to kill you."
Rosencrantz lifts up a feather and tennis ball.
Rosencrantz: You would think that these this would take longer to fall than this. (drops them) ...and you'd be right.
Rosencrantz finds a set of pots arranged like a Newton's Cradle. He gives the pot on one end a light tap, the pot on the other end bounces. He tries it again, same thing happens. He raises the pot so that the Cradle can start swinging, and instead they hit and shatter.
Rosencrantz wakes up with the prow of a pirate's ship crashed through the wall. He's still groggy and mistakes the figurehead on it for a real woman. Just he tries to kiss it, the boat pulls back and carries her/it away.
Rosencrantz builds a paper airplane and it flies around the castle before returning to him. When he next shows it to Guildenstern, it's an origami biplane. Guildenstern crumples it.
Rosencrantz and his giant sandwich.
Rosencrantz's outrage coming out of the "hawk from a handsaw" scene.