First time "Patrice" makes an appearance.
When packing up Barney's stuff from plays you can see a scuba air tank. This is from the famous scuba diver play he does in episode 5.8 The Playbook.
This episode is not narrated by Ted.
Kevin (Kal Penn) studied at Princeton University. It is possible refference to House M.D.
In House M.D. he worked at Princeton-Plainsboro Teaching Hospital.