When Peggy and Ed are in the meat locker, in the market, the inside latch has Canadian Robertson screws holding it in place. These screws would not be used in the US.
Kansas City corporate mentions signing up for a 401(k). Although that section of the code was enacted in 1978, the first 401(k) savings plan was introduced by the Johnson Companies in 1980.
Leinenkugel's Red Lager is on the shelves of the supermarket where Ed and Peggy flee (in 1979), even though that variety was first introduced in 1993.
Peggy talks wistfully about getting sent to a federal prison on the San Francisco Bay. There is no federal prison on the Bay. Perhaps she is thinking of San Quentin State Prison, or Alcatraz. Alcatraz had closed as a prison long before this episode takes place. Both of the facilities were also men's prisons.