Minor accidents occurred in these practice runs, including one on April 21. Arthur Campbell's vision was obscured by a dust cloud, leading him to strike the railing of a bridge. The car went into a stream and Campbell catapulted out of the car into some rocks, knocking teeth loose and breaking his jaw. Ralph DePalma, his riding mechanic, landed underneath the car and had to be pulled out. DePalma took Campbell's place in the competition, and the car was taken to a garage for repairs, though it is not clear if it was repaired sufficiently for the race.
