Here’s what I’m thinking. The duplicate bottle with the five of hearts is already in the large box at the beginning of the trick. The bottom panel of the inner box has a rotating mechanism which swaps the empty bottle for the duplicate and hides the empty in a false compartment in the outer box. The mechanism is triggered by the rotating latches on the boxes.
The box clearly has room for a preloaded bottle. Because the inner box is deep I’ll assume the empty bottle is hidden in the back or front side of the box. Possibly just a spring loaded false bottom flips up to hide the empty bottle in the side panel exposing the preloaded bottle at the bottom.
The coin through the glass must have been done with a magnet to slide a coin underneath the glass to the point where it is dropped into Teller’s hand. I think the part about turtles is that he used a coin shell initially when he used his own hand.
Or, a third idea: Maybe it’s a trick box. With a hinge. And a bottle with a 5 of hearts. 
mmm
She does a lot of TV ads lately for a weight loss product. And maybe the person who picked Marie is a Mormon from Utah.
Or maybe Marie Osmond was already on the list and somehow managed to wind up in the 42nd* slot.
mmm
*(I think it was 42, wasn’t it?)
I laughed when he said 42. It IS the answer to, well, everything (unless it’s the 3 of clubs!).
He definitely stumbled when dismissing the “sleight of hand” as if there could be an alternative definition that he was playing upon. So I am inclined to agree that the cookie is different and can be sensed by touch. Perhaps ridges were shaved down or alternated or maybe even a bevel down on the filling side such that the edge of the cookie is narrower?
I dunno, that still sounds mighty risky. I’m not sure they would allow that on the show (or that the performer would take that much of a chance).
mmm
All it takes is a magnet to detect a razor blade in a cookie.
I know and I knew right away no one was ever at risk. Relying on his knowledge and practice at the routine would also not be allowed.
But where is the magnet? Implanted in his finger, maybe?
Probably in the spinning tray. I think he had to be prepared to use sleight of hand to swap in a different cookie if Alyson decided to switch cookies at the end but since that didn’t happen P&T’s guess was wrong.
How would that help him find the cookie? The magnet would be spinning along with the cookie. You could argue that if he deliberately places the cookie on top of the magnet, then he’d be able to tell which cookie has the razor blade by tugging slightly on it. However, he always picks up the first cookie he hits without hesitation. Either he’s not testing it at that point, or else he was very lucky not to have encountered the razor cookie until the end. Come to think of it, the same argument applies to any other way of marking the cookie that requires touch to distinguish.
When he touches the cookie on the tray he’ll feel some resistance. If he hits the one with the razor blade on the first shot he’ll just fumble, or be ready to swap another cookie in if needed. It may look like no hesitation to you but he’s surely practiced this thousands of times and can sense the razor cookie. All that assumes that he can’t see the cookies, and Penn didn’t even think that was the case. He’s got outs all over the place on this one.
Revising my guess. The smaller box has no bottom at all. When Darcy places the empty bottle in the box, it actually goes into the table. The bottle with the five of hearts is waiting in the larger box on top of a bottom panel which latches to the smaller box when it is inserted.
There could be more than one magnet, or a large iron plate in the tray which essentially makes it a large magnet. Only the cookie with the razor blade will be attracted to the magnet. But you will notice he appears to be mixing up the cookies on the tray initially, if he is using a small magnet in the tray he would actually be doing that to locate the razor cookie over the magnet.
So this is basically the same scenario I described—he needs to pull the cookie in order to detect whether it has a razor blade, and got lucky that he didn’t find it until the end. I’m still not convinced that this is how he does it—it would have looked bad if he had selected the razor cookie earlier in the trick and had to hesitate or fumble in order to cover this. If he’s really polished the trick, then he’s found a way to always select the razor cookie last, which means that at the time of selection he can detect it without manipulating it, or that the turntable is rigged in such a way that when it stops the razor cookie is never under his hand.
You need to look at a video of this again. He fumbles a lot. At the very end he has a choice of giving the razor cookie to himself or Alyson. He could make that choice with any of the cookies. There’s nothing smooth about his actions, his blindfold is an excuse for his fumbling, certainly not causing it since he can obviously see the cookies even while wearing it.
I don’t know if he used a magnet but he could have. It is much simpler than you seem to think, which is a sign of a good magic trick.
I don’t like the magnet theory because it introduces an uncomfortable level of risk.
Could the razor blade that he inserts into the cookie be a fake? (did he claim no sleight of hand? I don’t recall).
mmm
On rewatch, it looks to me that the cookie with the razor is visibly different from the others (which is why it’s relevant that he’s wearing a blindfold to mislead away from that, and why it’s relevant that Penn says the blindfold is fake).
In which case, part of it is him doing an okay job of showing the cookie that gets a razor put in it, and then he — spills out some other cookies, and then moves them around three-card-monte style, and then spins them, and then eats them so the audience (including Penn and Teller) never sees them up close, and Alyson (the one person who could get a good look) is blindfolded because — well, yes, it makes the act more sinister; and it makes the reveal at the end funnier; but the trick, as presented, doesn’t require her to be blindfolded.
Except, on rewatch, there’s a big fine dot on the center of one cookie: it’s a dot that you wouldn’t see if you’re an audience member viewing the side of the cookie, and a dot Alyson that can’t see if she’s wearing a real blindfold — but it’s a dot that he can see if he’s wearing a fake blindfold, the way that Penn said.