Charles,
This stabilized version shows a little more detail, but I still wouldn't want to say he is checking his watch (he could be, but I can't tell). There is a slight 'interference' just as the motorcycle rider (McLain) leaves the frame to the left. There is a film splice just at this time when Atkins appears to jerk his head.
When composing the stabilized GIF in reply #4, I saw something I've not noticed before. At 18 frames in the full Hughes clip, Camera Car #3 is smoothly ending its turn to Houston street but then abruptly takes a jump forward of about 3 feet in just 1 frame. This is about 3 times faster than the film's rate. At a frame rate of 18.3 fps (Dale Myers} each frame clocks about 55 ms. A car speed of 10 mph would advance 14-15 ft per second (0.8 ft per frame), or 3 feet in 206 ms. At 5 mph the interval is still less than half a second.
Basically, the film is missing 3-4 frames during this forward jump, which would be typical of a simple frame splice. But here is the rub. There is no splice bracketing this event. A careful analysis of the scene frames, as well as for 20 or more scenes filmed by Hughes, shows a startup frame (first frame overexposure) for the first frame following the jump. Meaning Hughes released and then enabled the shutter in the blink of an eye. Intentional, or reflexive actions? The head turns noted by Charles Collins of Atkins and his left side passenger in Camera Car#1 follow by about 1 second.
James