After P-Ranking Crust Cove in Swap Mode, there is a 1 in 1000 chance a grey door will appear where Gerome is. This door is speculated to lead to Gaster from the hit indie game Undertale by Toby Fox. When asked about this, McPig said 'get out of my house or i'm calling the cops.'
Contrary to popular belief, the 'neoruins' tileset found in the game's files is not unused. It IS used, but only in one single room. that being where you find the Man behind the tree in Chapter 1