I feel like this has been fixed in previous updates, but I am yet to find anything beyond June 2016.
Anyway, as explained in this reddit post, the glitch does, basically as a glitch would normally do: break the game. In this case, it's no different.
Exploration revolves around timed triggers, and a list of random events. As you would see from following a Dweller's log when they have been sent to the wasteland, a random event triggers roughly once per minute.
To quote the above link:
From what I have noticed, the game seems to have random trigger times for incidents and also for dweller findings. When you moved you clock ahead by 24 hours, you caused the explorers event to trigger within that 24 hour period. When you move the clock back, it will take another 24 hours for them to have any more experiences because the game assumes they have already been completed. I've also noticed that if I still have a dweller out that has been affected by negative time travel, any dweller I send out will not collect anything either.
Basically, the amount of time does not determine event triggers, rather, the time changing.
If you keep reading the above link, you'll notice that this glitch can have various game-breaking effects. However, as is the glory of this game, you can close it down, wait 24 hrs, then re-open it with no ill effects, and the intended equipment you desire. With the addition of Nuka-Cola, you can also negate the return times of your Dwellers.