Continuity mistake: There are some large cracks on the wall left from when Captain Boomerang pinned Flash to the wall for a moment. When the gray adhesive traps Flash against the same wall again, the bottom most crack is to the right of his head. Then when Flash begins vibrating his arm to throw the adhesive and the bomb at Reverse Flash, the crack is suddenly on his left side. It switches back and forth during the scene.
Picture added by Quantom X