The pilot has the canopy slid back for some reason; odd, but not impossible: there'd be some airspeed above which the canopy had to be closed but below that, no problem. The plane is landing, incidentally (airbrakes are deployed), so there might be some problem and the pilot is cautiously making sure he can get out if it all goes pear-shaped.
Wrong model F-86, anyway: the rocket-armed one was the F-86D, which only had about 25% parts commonality with the basic F-86.
Cockpit open on landing is a carry over from WW2 days. Pilots would open the canopy to get a better look at the ground or carrier deck as the landed. It was discontinued as command and controls got better and planes got faster on landings.