The ring that Sam wears in this episode is Jared Padalecki's real wedding ring.
The tweets Becky tweeted were actually real. They can still be found on the twitter account superbeckyrosen.
In the beginning of the episode, Sam positions Dean to stand at his side at his wedding. In real life, Jensen Ackles was a groomsman in Jared Padalecki's wedding, and vice versa.
Garth is previously mentioned in S6E4 Weekend at Bobby's (2010), when he calls for advice on a vampire he's hunting and we hear Bobby's side of the conversation.
When Sam is gagged he says "fuck you" to Becky. However Becky believes he said "I love you" and replies that she loves him too.