Lonny Flash says in order to get the mold for the key he had to "play the kid in a very X-rated version of Kramer vs. Kramer. The film Kramer vs. Kramer was released in 1979. The novel, though released in 1977, wasn't published until September of that year. This episode is set near the end of June 1977.
Flashlights in the 1940s would be incandescent. The flashlights used in the Auschwitz escape are a much cooler color, like a LED flashlight.
One of the guards in the bank it's wearing on his gun belt at the small of his back a small pouch which is used to carry a pair of rubber gloves. That type of pouch was not even created until the late 80's or early 90s at the earliest. Uniform police officers and guards did not carry rubber gloves on their person as a rule back in 1977. They became a popular item For first responders to carry after the AIDS virus.
The series is set in 1977. In this episode, Lonny Flash (Josh Radnor) makes reference to "Kramer Vs Kramer", a film which didn't come out until 1979.