Alexandra Holden plays 2 different characters on Grey's Anatomy (2005) (as Jamie) and Private Practice (2007) (as Laura). Both characters are the patient of Dr. Addison Montgomery (Kate Walsh).
The character Sam Bennett's nickname/pen name Dr. Feelgood is most likely a reference to the album 'Private Practice' by the band Dr. Feelgood released in 1978.
Idina Menzel played a brief love interest of Tim Daly's character (Pete) in Season 2 when in reality, she was married to Taye Diggs (Sam). There's even a scene of Sam approving of Pete dating the Idina's character.