When Jimmy comes back from his rite of passage, it is supposed to be near sundown but the shadow beneath him as he stands up is short, indicating that the sun is directly overhead.
During a thunderstorm, the lightning and thunder don't always exactly coincide. This only happens when lightning is directly overhead, as light travels faster than sound. Usually, there is some lag time after the occurrence of lightning before you hear the thunder.
When the posse has the Indians under siege, at one point what appears to be a searchlight crosses the smoke.