Right now this new glitch can't do anything for speedruns of the game, but it might has a potential of breaking the game completely.

Check out these two videos with the demonstration of this glitch and the possible outcomes:

So, the thing is: if you reload a mission just quickly enough to not make the "mission completed" screen block the Esc button, but at the same time you'll be slow enough to not reload it too quickly before the game actually counts it as a completed mission - you will be in the state of that mission, but actually in the free roam city.

This glitch is really hard to perform intentionally. The timing is always damn insane. But I wonder what would the game do if the mission, for example, had a timer. What would happen when this timer runs out, but you are actually in the city and not in that mission.

In some games this type of glitches leads to the save corruption and to the unlocking the final missions of the game early and etc. So, this glitch needs exploration. I tried to catch this just a year ago when I started speedrunning this game and I couldn't, because the timings are barely humanly possible. And I thought it IS impossible. But no, it's not. There is a possibility to break this game in a somehow useful way. And one day it'll be found.

Okay, I tested it on Whack-A-Mole. Timer doesn't appear in the city... So the theory is broken. But I also noticed, than menu is really broken in this state: It does nothing useful, however.