Any chance the tiles have physics bodies attached?
I had an issue that @slembcke helped identify where I was building a maze with small pill segments. The start/end positions of two segments were identical. In debug mode, there was no issue, but in release mode it was causing a div/0 issue causing the physics to go crazy and exploding the screen.
The fix was to slightly offset the start/end points by a wee bit:
[CCPhysicsBody bodyWithPillFrom:ccp(0, 2e-4) to:ccp(size.width, 1e-4) ...