When Dean lowers David by rope to the bridge span below, David paints "Cathy" with a "C" in the close-up shot, but a moment later in the wider shot, it appears to be spelled "Kathy" with a "K". When the police car leaves and Dean in seen in a wide shot pulling David back up on the bridge, the bridge span is clean with no paint at all.
In the final scene, when David is getting ready to run his race, we see it is overcast/misty. When the shot switches to the crowd, it's clear and sunny. Back and forth, from cloudy to sunny.
In the locker room, while speaking with David, Burton starts putting on his tank-top twice.