The coin tossing, for one. The law of probability stands firmly against that many "heads" in one sitting.
The arrivals and departures of these two are quite ironic as well. They seem to just appear and disappear at will. It is an absurd bit of theatre.
The deaths of R and G are never reported in the play, even though the audience expects this event. This is one of the themes of absurdity and the believeablity of theatre--that people believe what the actors want them to believe. By this idea, we should believe that R and G are still alive and never died even though we know the opposite is true in Hamlet.