Where was the continuity person with this episode? This would've made perfect sense if the character from the past was Bill, but for some reason they had to wedge in a character named Tom who simply does NOT fit in the chronology of the show.
For instance, Tom talks about Mary's "roommates" from when they had their apparently head-over-heels love affair 2 1/2 years before. But would that put Mary back in her hometown right before she moved to Minneapolis - BUT SHE LEFT HER HOMETOWN BECAUSE OF BILL! Was she cheating on Bill the medical student with THIS guy?
And who plays Tom? Joseph Camanella! A magnificent character actor, yes, but... but...
He was 49 years old when this episode was made! To put that into perspective - he was only 4 years younger than Nanette Fabray, who was playing Mary's MOTHER that season! Even more astonishing - Harold Gould was 50 that year - playing Rhoda's FATHER! And he looked YOUNGER than Joseph Campanella IMHO.
I know, I know, get a life. But I've been a huge fan of this show since literally childhood... 168 episodes and this is the only inexplicable one. (The sub-plot of Ted going to Washington was very well done, and welcome comic relief).