Yo, I was playing the demo and I think I was in the room in the 2nd lv where u get to see the boss passing by a door, well I was spamming slide and melee in a specific spot in the room and got glitched out back to the beginning of the level. I couldn't go back in because the door had the red skull lock so it couldn't open. I just came to report it have a good one. Its extremely fun to play this demo you should be proud of yourself.
edit: btw u can skip the obstacles in the cerberus fight but just parkouring yourself over the lava with wall jumps