When Stanley is talking to/yelling at Peter Menzies next to the tombstone, he begins by standing behind the tombstone with his right hand on it. Later he goes to one side of it and yells at Menzies. All of a sudden he is behind the tombstone again, right hand on top of it and is much calmer, definitely not the state he was in a moment before.
One of the characters is executed in 1958 for a murder committed in Maine the previous year. Maine outlawed capital punishment in 1887.