Historical Roster size
 

In historical game, the NHL roster size through the 1930's is 20 (17 dressed), but for the 1938-39 season it suddenly increases to 23 (17) , before reverting back to 20 (17) for 1939-40 season.

I'm not sure if this is intentional, but there was no mention of the change in the historical notes for 1938-39 season, so I suspect it may be a glitch.

Yeah, 38 was set to 23 players in the database for some reason, I think I lowered all of them at some point and just missed that year. I'll change it to 20.