After escaping the elevator Lea walks past a door marked 301 indicating he is on the third floor, after looking out the window he opens the door to the stairwell where there is a door marked with a two (2) indicating the second (2nd) floor. He entered the stairwell on the third floor so he can't be on the second floor.
When one of Colonel Mokrani's men sees people running through the parking lot of the supermarket through his sniper scope Morkani looks through his own weapon sight to see the same thing. However Morkani's sight is an EoTech red dot sight which has no magnification power at all and would be useless in that manner.
According to Google maps, the distance between the NOEMA Observatory and Grenoble is 95 km, & takes almost 21 hours to hike one way, but the soldiers, scientist & a little girl walk there, have a battle, run around the supermarket, and have time left over for the soldiers, a badly wounded man, & the scientist to walk back all in the same day.
When at the hypermarket, after the first soldier is shot from the roof the rest of the squad doesn't take cover behind the nearby cars.