When Johnny Cage is fighting Scorpion, and he does his human spear, Johnny runs until he stops at the tree. The spear then catches up, and becomes wrapped around the tree in front of Johnny. When the camera changes view, the spear is just leaning on the tree. The camera changes view again and the spear is wrapped around the tree again. When Scorpion pulls the spear back, it goes straight back, and doesn't unwind around the tree.
The autographed photo of Johnny Cage that lands among Scorpion's remains is a reference to Cage's 'Friendship' move from Mortal Kombat 2 (a sort of comedy finisher where after beating your opponent to a bloody pulp you would then make peace with them by giving them a present or putting on a little show instead of killing them). Apparently many fans considered kicking the tar out of somebody and then giving them a signed photo of yourself to be incredibly egotistical, hence why it appears in the movie.