Goodman's car starts out of nowhere and the people blame Goodman just because his car started and not the others so they think that Goodman is the alien. They are not thinking it through and they are starting to blame innocent people for they are doing nothing.
Charlie's light go on all of a sudden and they blame him for doing this and they think that he is also the alien for turning them on without turning on the light switch when he was outside with the rest of that mob. They are just going straight for conclusions and not thinking on what they are doing.
For saving his life, Charlie blames Tommy so the mob won't be so attached to him and then everyone started to complain that Tommy is the alien because he told the mob that people from space (aka: Aliens) sent 4 aliens down to earth and disguise themselves as a family of 4. A Father, a Mother and 2 children.