I would tend to agree.
Based on the movie… I just reviewed the scene, and first of all, it was a terribly quick cut. We don’t even see the Prince until he already has the vial up to his nose. 
So, it seems reasonable that he’s been able to gather some clues already from the table, from Vizzini’s body, etcetera.
The book isn’t terribly helpful:
Now everybody’s got me thinking about just what steps the Prince would have had to follow to track Fezzik, Inigo, and Vizzini to get back Buttercup.
Beginning with the premise that the Prince knew where Buttercup went riding and told Vizzini to wait there doesn’t count — at no point can the Prince make any deduction in front of his guards that comes from the knowledge that he himself sent Vizzini or arranged the whole thing. However, we can grant the Prince the uncanny ability to track people from the tiniest clues — and the discretion to ignore clues if they give away his own complicity.
So — Vizzini captures the Princess, takes her to the boat launch, puts the fabric from the uniform of an army officer of Guilder on the saddle of a horse, and slaps the horse to send it off for later discovery.
The Princess’s horse likely returns to its stable, or heads in the direction of it. If the Prince were playing it safe, that would be the moment he’d allow himself to know Buttercup had been taken. He can’t leap to the conclusion of kidnap too soon.
Humperdinck can either follow Buttercup’s horse’s prints out from the stable, which is the colder trail, or follow the incoming hoofprints back to where the horse came from most recently. He’s allowed to suspect, because of the fabric on the horse, that the kidnappers are taking her in the direction of Guilder. (He could announce suspicions, for the benefit of the guards, that it was only a ruse; but I don’t see what that achieves for him.)
He knows the incoming horse trail is more recent, but not if it’s shorter. He might track them both — Count Rugan suggests they have the ability (“shall we track them both?”).
Assuming they track both, they find where Buttercup was captured by three men on foot: one medium-sized, one short, one very big. The tracks lead to the boat launch, meeting up with the track of the horse.
The Prince could probably see that the horse was startled away, dashing away quickly in response to something, but he’d probably keep that to himself. Knowing the horse was driven away deliberately leads too strongly to the conclusion that the horse was meant to be discovered, and that the Guilder thing might be a ruse.
So now he’s got footprint samples in mind for the tracks of his three perpetrators: he probably recognizes Vizzini’s tracks — that is, unless he hired Vizzini in a letter and not face-to-face — but may not recognize Inigo’s and Fezzik’s. Vizzini hired them personally.
As the tracks do not lead away from the boat launch, he can assume they took a boat. He probably follows the Guilder lead and makes in that direction personally, and sending off some other boats in other directions to inquire about a traveling party of a giant, a man, a woman, and a short guy.
How does the Prince get from the Boat Launch to the Cliffs of Insanity? At what point does the Prince privately know that some outside agent is interfering with Vizzini’s plan? Does Humperdinck suspect this before he finds Vizzini dead? How does he know that Westley’s prints at the Cliffs aren’t part of the plan?
Fish, a lot of that strikes me as beyond the point. The prince had a reputation, fairly earned I think, for being a remarkable tracker and huntsman. Thus, as long as he acted like he was seeing something that the soldiers didn’t as he followed the route, they wouldn’t really suspect anything odd. He could even comment on seeing little bits of the track that none of them could make out.
As far as knowing something was wrong, that the Man in Black was interfering with Vizzini’s plan, I think that would have definitely been clear when he found the traces of the fight on the clifftop. Vizzini and he had to have colluded as far as some details as to where the Prince should expect to find the princess, etcetera. Something remarkable, like a fight between two master swordsmen, before that point would have attracted his attention.
Going back to the book, that doesn’t cover any of the stuff with the prince up to the Cliffs, but it does mention that he was able to spot traces of what happened on the cliffs himself… that a man climbed with no rope for a stretch near, but not quite to, the top. That would also have been unusual enough to be disturbing.
All speculation, of course.
Sure, up to a point he could’ve just rode along a pre-determined trail without having to make much comment.
But right around the time where we pick up the Prince’s tracking, at the scene of the swordfight, Humperdinck has already managed to reach the Cliffs of Insanity on horseback. So he didn’t climb the rope — there was no rope, then — but he was planning not to climb the rope if he’d brought horses.
Also, he sees a swordfight between two masters. He knows that one lost and lived, running off alone, and the other followed to catch Vizzini, Fezzik, and Buttercup. Since he’d probably been on the scene of Buttercup’s capture, he probably knows what Inigo’s footprints looked like, so he probably knows Inigo was the loser of the duel and something was wrong.
But he might have known before that — if he’d seen Westley’s boat at the base of the cliffs. Did he have any reason to visit the base of the cliffs? I can’t think of a way for him to have known.
And if he hadn’t seriously been tracking Buttercup and identifying her captors — just riding glibly along to a predetermined meeting point — he might have assumed that Vizzini’s hired sword had won.
I’m just trying to figure out when he knew: he definitely knew when he saw Vizzini dead, but when before that could he have been certain?
Moving this to Cafe Society isn’t fair. It’s just fairer than death, that’s all.
At least Fish got it right. It’s ** Westley**, with a “t”.
It wouldn’t surprise at all if wine was the link. Goldman also wrote “Year of the Comet”, a film dedicated to his love of wine.(Which he credits as the reason for the complete and utter failure of the film for.)
Anyone else get the feeling that we’re all putting a lot more thought into this than Goldman ever did?
re: getting to the top of the cliffs, yes, he landed his boat somewhere else and rode to the top. He might have had enough reason to sail by the base of the cliffs, and seen two boats there. That’s a good hint, and one that I should have thought of.
My next point is that as soon as he spotted any of these clues - the boat, the trail on the cliffs, the swordfight traces, the Prince would have known that somebody else was interfering with the plan. He wouldn’t have known if the interference was purposeful or accidental, (not that he’d have cared too much I think,) and he didn’t know if the interference would be enough to ruin the plan. For instance, if Inigo had won the duel, the effect of Westley’s interference would be minimal, but he’d still have interfered.
Smeghead, of COURSE we’re putting more thought into this than Goldman did! Isn’t that the fun of this kind of thread?
