As Sawyer pulls Jack off of Locke, his face blur's as you would expect as his head swings around
But for 1 single frame his face comes into focus
I think it dose not look like Sawyer, It looks like a face has been photoshoped onto the frame
SlowMotion clip.
Note: Im sure many peope may not agree with this, but having looked at Lost closely for so long in such detail, This frame looked strange to me.