My best guess, based on my collection (I have all the editions, and duplicates of several), is that when it came to everything but the puzzle roll, the Milton Bradley folks just used up whatever inventory they had, and then printed (or pressed) new stuff as needed. I once had a chart listing all the prize cards for each edition, and I was told by a few collectors that even those were not completely consistent in some cases. Also, if you got your copy second-hand (as almost all of us have), you can never be sure that it didn't come from a home that owned multiple editions and got the pieces mixed up over the years.