Broken room link
A broken room link is a room link that changes the level into a structure that could not exist in real life. Exiting a room on one side will bring the prince into a room that does not have the previous room attached to it, at least not at the side it would be in real life. For example, if the right room link of room 22 is 5, and the left room link of room 5 is 5, exiting room 22 to the right will bring the prince into room 5, but subsequently exiting room 5 to the left will not bring the prince back to room 22. Instead, the prince will reenter room 5 on the right.
In popular culture
In The Matrix Revolutions, Neo (Keanu Reeves) is trapped in a subway station, running back into the same room over and over.
In the Portal puzzle-platformer series, a portal gun can be used to create visual and physical connection between two different locations in three-dimensional space. This can create situations similar to broken room links, as can be seen in this fictional live action footage.
The film Cube 2: Hypercube also features (many) broken room links.
More examples in the forum: http://forum.princed.org/viewtopic.php?p=19857#p19857