Looks like you can edit stick lengths to be shorter than the minimum length the engine usually allows. Upon playing the level, the links will correct themselves one at a time - resulting in replays that can be different several times in sequence.
MetallicDragon demonstrates it with this handy level.
Until Pacifist gets a chance to put a fix in, if you are experiencing any inconsistencies please make sure you don't have any really ultra-short sticks anywhere in your contraption.
