The "unknown" hero is described as having blue eyes. Gerard says that matches Kimble's description. But the wanted poster he is looking at says Kimble's eyes are brown. This mistake actually happened several times during the series because the show was originally filmed in black and white and the prop posters were printed saying "brown" even though David Janssen had blue eyes.
The sheriff's wife secretly hands Dr. Kimble a set of keys while he is in jail to open the door after everyone leaves. The camera cuts to show the keys, and one can see that they are blanks and would not open any lock. He later is shown unlocking the jail door and escaping.