After the first commercial break, the scene is Steve and Mimi in the Warsaw, angry at each other. However, they make up, and decide to combine their bachelor/bachelorette parties together. They leave to "do it in the alley." Lewis and Kate enter right as the other two exit, with no dialogue among the four. Later, Kate tells Lewis that she's going to tell Drew she loves him "at Steve and Mimi's party." Drew, listening through a pipe, says, "That guy's gonna be at my house?"
How did Kate and Drew find out about the change in party plans? Kate didn't talk to the two, and the only chance for Drew would be if he saw them while they were in the alley.