Albert takes a horn off the pub wall and blows into it, but in the next shot, it's back on the wall without his having put it back there.
Rose does correctly calculate the number of possible orderings of 12 different postcards: 479,001,600. However, that would make the odds of arranging them back into their original order 479,001,599-to-1, not 479,001,600-to-1 as stated.