I don't think that anyone outside of the Mob even knew what "making" a guy meant back when the movie came out. FFC probably had no real idea of the significance of it within the Mafia.I mean you have Michael doing the hits on Sol and McCluskey,the massacre of the other Bosses,and the power and wealth he brought to the Corleones. Surely at some point ,he would have "taken the oath",but I don't recall any mention or reference to him getting made.
I think that if the movie came out today,you would almost have to include a formal making ceremony,and at least a few mentions of "made' guys,because the movie-going public is more aware and sophisticated when it comes to Mob matters than it was in 1972.