1953:

 

 From "Paging the Crime Doctor":

 

 

 The episode is set in 1993.  1993 minus 40 years = 1953.

 

 Oddly, in the same episode, Bruce looks in Leslie's yearbook, the Caduceus, which feature pictures of Thomas Wayne & Matthew Thorne.  The odd parts are the 2 numbers next to each picture:

 

         

 

 1907 & 1908?  It can't be the year they graduated because they all graduated together, and it's also said that Benny Goodman played at the Waldorf that week; Benny Goodman wasn't born until 1909.  It's possible that these dates were intended to be the years that each student was born, but that doesn't make much sense either as Matthew Thorne would be 86 years old in the episode in question - making his storyline about desperately wanting his medical license back to own a real practice unlikely.  The only out I have on this one is there's nothing indicating that these numbers are the dates they were born.  They could indicate many things I imagine.  For instance, it's possible the number in question is the enrollment number, and Matthew & Thomas being such good friends enrolled together explaining the single digit difference; just one of several fun theories, with not enough evidence to support or disprove them.  As it stands the numbers don't mean anything to me really, which is too bad, but as continuity flaws go these are extremely minor.

 

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