When Odysseus requests that the cyclops give him a gift which is required by the law of the gods, the cyclops refuses. Odysseus informs the cyclops that it is the law of Zeus who insists the host show hospitality to his guest. It is immediately obvious that Odysseus and his men are going to face danger from the cyclops. The cyclops is not going to treat Odysseus very kindly. This is a sign of foreshadowing, hinting that Odysseus is going to have problems from the cyclops. Odysseus's request for hospitality from the cyclops is met with rude rejection. The cyclops in turn eats Odysseus' men:

Scorning the gods, Polyphemus grasped two of Odysseus’ men and slammed their heads against the ground. He then proceeded to eat them whole.

The cyclops is not going to welcome Odysseus and his men. Instead he is going to eat them all if he gets the chance. The fact that he had two more men for breakfast foreshadows the danger that is to come:

When the Cyclops awakened in the morning, he ate two more men before taking his sheep to pasture, leaving the dreaded boulder behind to block the exit.

It is obvious that Odysseus and his men are in danger when the cyclops puts a boulder on the cave. This is the foreshadowing or hinting that the cyclops is going to keep Odysseus and his men held hostage. He is planning to have breakfast and dinner on Odysseus' men:

He devours two of Odysseus’s men on the spot and imprisons Odysseus and the rest in his cave for future meals.

No doubt, Odysseus and his men are in trouble. They are going to be eaten by the cyclops. Odysseus and his men were treated with a lack of respect. The cyclops showed no hospitality. Odysseus begins to realize that he will have to devise a plan to escape the cave of the cyclops. He has no choice but to blind the cyclops. 

What are three examples of foreshadowing that hint that Odysseus would have problems with the Cyclops in The Odyssey?

When looking at foreshadowing in The Odyssey, one thing to be aware of is the overall structure of The Odyssey as an epic poem. It begins in the middle of the story, long after the Cyclops episode has taken place. Odysseus's encounter with Polyphemus has already happened and is long past, even as it has yet to be recounted in the narrative itself. A significant portion of The Odyssey involves Odysseus recounting his tale to the Phaecians, who offer him hospitality when he washes up on their shores. This structure allows future events to be alluded to quite boldly, in ways which would be much more difficult to achieve had it followed a more conventional story structure, running linearly from beginning to end.

The Odyssey begins while Odysseus is trapped by Calypso, towards the end of his many wanderings, and while Odysseus languishes in the nymph's keeping, we see the gods discussing what to do about him. There, Zeus mentions the following, in response to Athena (Odysseus's chief advocate among the Olympians):

Now, how on earth could I forget Odysseus? . . . No, it's the Earth-Shaker, Poseidon, unappeased, forever fuming against him for the Cyclops whose giant eye he blinded: godlike Polyphemus, towering over all the Cyclops' clans in power. (Fagles, Book 1, lines 77-84).

This is in the very beginning of The Odyssey, and already we have some sense of the wrath that Odysseus has engendered from Poseidon, and the reason for it.

Later, as we are introduced to the Phaecians themselves, we learn more about the Cyclops collectively. As the poem tells us:

years ago they lived in a land of spacious dancing-circles, Hyperia, all too close to the overbearing Cyclops, stronger, violent brutes who harried them without end.

(Fagles, Book 6, lines 4-7) Already, we know that Odysseus had blinded a Cyclops and earned the enmity of the god of the sea, now we have more of an idea of the kind of people Polyphemus belonged to, and can form additional expectations as to the nature of this encounter, one that still has yet to be revealed to us. Finally we witness Odysseus announcing his identity to his rescuers, and begin reciting the various adventures and hardships that had brought him before them: only then do we visit Odysseus's encounter with the Cyclops. (Fagles, Book 9).

In his account, Odysseus frames the episode thusly:

From there we sailed on . . . and reached the land of the high and mighty Cyclops, lawless brutes, who trust so to the everlasting gods they never plant with their own hands or plow the soil. . . . They have no meeting place for council, no laws either, . . . each a law to himself, ruling his wives and children, not a care in the world for any neighbor. (Fagles, Book 9, lines 118-128)

Now we know that they are lawless, part of a culture which exists outside the bounds and rules of civilization (which is a common theme in The Odyssey). Even though he is only beginning this part of the story, between what we know already and what he's just told us, we can already infer much about the opponent he is about to face, that this is someone both hostile and powerful, and we already have some idea as to the way this encounter will end (and what this resolution will mean for Odysseus going forwards). All this and we have yet to meet Polyphemus himself.

Note: The following translation was used in preparing this response: Homer, The Odyssey. Translated by Robert Fagles. New York: Viking Penguin, 1996.

What are three examples of foreshadowing that hint that Odysseus would have problems with the Cyclops in The Odyssey?

First, the Cyclopes are described in the very beginning as "dealing out rough justice to wife and child." Obviously if they have no problem treating their families violently, they would probably have no problem treating a stranger with violence.

Second, when the Cyclops came home, he used a big rock to cover the entryway. It is at this point that we realize that Odysseus and his men will not be getting out. This foreshadows that there will be a confrontation for them to get out.

Lastly, when we learn that Posideon is the Cyclops' father and that Odysseus messed with the Cyclops' and add to that that Posideon is the god of the sea where Odysseus needs to travel, we can anticipate that Odysseus will have problems.

These are the instances I see in the Cyclops section. It may be that you were looking for something else and another editor might point it out to you.