The "young" versions of the doctors were done with CGI.
The title of this episode, "Love Of My Life," is a song by Queen.
The convention featured in this episode was filmed in the beautifully ornate Millennium Biltmore hotel in Los Angeles, USA. The same filming location used when Alex Karev went to find Paul Stadler in S13 E23 titled True Colours. It is a popular filming location and has been used in many films, music videos and TV shows.
"Love of My Life" is a song written and sung by Carly Simon, from the 1992 film "This Is My Life (1992)".