Same footage used twice. Rear facing shot of police chasing the race car after turning left. Closeup, gas station, another closeup, then back to the police car with the same car traversing in the background. Also, in reality the chased car would have been further down the street and not back at the corner.
Race at the beginning of the film during the speed shift: Stewart-Warner under-dash, three-gauge cluster of temperature, oil pressure, amperes. Needles all at their static and initial state signifying the engine is off. Also, the doohickey hanging from the key chain moves marginally (from the heavy foot clutch action) and not fore and aft as it would under acceleration if actually shifting gears.
The type of car changes during the street drag race. The race starts out with a 1952 modified Chevy on the left. The car modifications make it look like a "gasser" drag race car (it's actually a street freak). This car does not have a front bumper and has a solid front axle. The car that crashes is a stock 1952 Chevy, complete with front bumper and stock front suspension.