Goofs

When the character Dr. Helen Cagle is introduced, the narrator says she works at "John Hopkins University." The name of the school is Johns Hopkins University. A chyron later spells the school's name correctly.

Edward and Anne's headstones say they died in 1975. The pistol used to kill them was a Beretta model 92, which was not produced until 1976.

When Richard goes back to inoculate his mother against polio, he brings booster shots. However, they never explain who or how the booster shots were administered. Either Richard had to stay until she was at least 4 (last booster age group for Polio) or someone had to have been given the booster shots and been complicit in providing them once Richard went back to his time.