Just after the 3 o'clock car incident, Don returns to the diner. As he sits at the counter his wristwatch reads ten minutes to two. Then, when He moves to the booth his watch says 9:20 while the diner clock says 3:15.
Don puts two pennies, not one, into the fortune telling machine before asking the question, "Is it really going to be four hours before we're going to get out of here?"
In most of the diner shots, Don Carter's right sleeve is smooth. But when he steps out of the diner, walks to the park and they talk, there is a big pucker in the middle of the sleeve (like a hanger end bump).