If the player enters Threed's circus tent and repeatedly uses the Check command on the rightmost corner, the game will glitch in a variety of unpredictable ways. The most minor of these outcomes involves a short delay in when the "No problem here." text box is thrown up, while more major results can escalate into full-scale corruptions; most results involve the text box spewing garbage data. The reason for these phenomena is because of a programming oversight: the game stores every map in a single file that players are transported around via warps. However, the corner where the glitch occurs contains a gap in the room's boundaries, enabling the player to use the Check command on out-of-bounds areas that the game was not programmed to read.

Following its discovery, the bug, popularly known as the "Threed Tent Glitch" and the "Check Area Glitch," became a key asset for speedrunners, as one possible effect gives players access to a debug menu, from which they can warp directly to the game's epilogue. Its utility only further increased after players discovered that it can be triggered very early in the game by using additional glitches to reach the top-right corner in Onett's map, which similarly gives access to an out-of-bounds area.