Security hole in mcdonalds monopoly

So after giving into the monopoly craze again, I was punished by finding I was given a box of chicken selects, minus the monopoly stickers (an older box). Refusing to be taken, I went back to get a fresh box with a chance at new properties. I was given one without any problem, it was very busy and they didn't want to deal with me. It occurs to me that this unmarked box is the golden ticket, and could get me free boxes across the city without having to actually pay for food.

I now have 3 of the 4 railroads, finding shortline will get me 5 million. I have 2 of the 3 greens, I need Pennsylvania.