It was nice to get to know a little bit more of Colby. However, what he did was wrong. After he suspected of his friend and then heard what he told him he would've done the right thing by talking to Don and let him take care of it. Instead, he doesn't do it and he almost ends up losing Don's trust.
Charlie... He's very young and sometimes I think this is why he behaves and thinks in a certain... immature way. But that's where Alan comes in. He talked to him and Charlie realized everything else on his own.