When JD is yelling "In your face" and turns around to find Dr. Cox staring at him, Snoop Dogg Intern is behind both JD and Dr. Cox as the camera switches back and forth.
When giving out favors Dr. Kelso refers to Frank Encarnacao as Dr. Carlson. Later in the series the same actor is known to be named Dr. Mickhead.
Dr. Murphy uses the term Blennorrhea, an antiquated medical term for a mucous membrane discharge. However, it's not uncommon to keep using antiquated names as long as everyone understands.
This is everyone's second year at the hospital, this shouldn't be the residents first time experiencing Kelso's anniversary.