By using the Coastercam on the Merry-Go-Around, a framed picture of a group people can be seen multiple times as part of the design. Unfortunately the quality of the image is too bad to be able to recognize who the picture is of.
Naming one of the guests "James Hunt" will grant the player a dune buggy which they can drive and run over guests with. James Hunt was a British racing driver who won the Formula One World Championship in 1976.
One of the available decorations is called the "Vampire Castle". Zooming in to one of the tombstones surrounding the castle will yield a grave with the title "RCT 2", implying that the game is now dead and buried.