This is the scene where Charlie killed his friend Pete Van Horn. This supports the theme by showing That Man is willing to kill other men
Mankind is his own worst enemy
This is the scene where someone punches Steve. This supports the scene by showing how people aren't listening to common sense and are doing irrational things.
This is when everyone starts to converge and go after Tommy, the kid. The shows that people are willing to go after people and things that in no way should even begin to be accused.
This whole play is about how mankind will be the end of itself. The whole point is the people are trying to find other people to blame to satisfy our need to find a reason as to why a mysterious occurrence is happening. Scapegoating even the most inconspicuous and innocent people aren't safe from the human and it's accusations and crazy conspiracy as to why something strange is happening. The point of this is to show that with the right trigger, the best of allies can turn around and rip each other apart. This whole struggle is all caused by the human mind and how it needs to have an answer, no matter how radical and outlandish that conclusion may be.