When looking into Zeitgeist's claim about three kings/wise men/whatever visiting Horus, all I could find in the source book was a reference to stars pointing at other stars, which has absolutely nothing to do with actual physical men visiting Horus on the day of his birth. Wouldn't that make the Zeitgeist claim false?
Well, that's not a dichotomy given that the Egyptians believed that the stars were embodiments of the "souls", or b3w(Bas), of both the gods and the deceased kings who had been resurrected and transfigured into gods.
But more to the point about three kings adoring the infant Horus (called Harpocrates by the Greeks), this seems to be implicated on the following magical gems pictured below. They depict Harpocrates/baby Horus arising out of a blooming lotus that is stationed within a barque. To the left are always three falcons, one of the major symbols of the kings of Egypt as well as of Horus himself (obviously), Horus being the god of kingship, the living king being believed to be the embodiment or avatar of Horus.
There are always three falcons, and as you can see on gem "A.", these falcons are each bearing a hedjet crown, the crown of Upper Egypt, indicating kingship. So here we have the infant Horus accompanied by three symbolic "kings". We also see Horus accompanied by three scarabs, three rams, three uraei, and three crocodiles, all of these animals are also symbols of the kingship of Egypt, and all are here depicted in triads, so clearly the number three is being given conspicuous significance here and is not just some arbitrary detail thrown out there to fill up space.
As scholar Dr Pieter Johannes Sijpesteijn wrote in his article Remarks on Some Magical Gems
Anno 69, No. 1/2 (gennaio-dicembre 1989), pp. 119-121:
Dr. Sijpesteijn wrote:
One is reminded of intaglios representing. Harpocrates seated on a lotus (in a papyrus boat) and surrounded by three crowned hawks, three snakes, three crocodiles, three goats and three scarabs (cf., e.g.,. C. Bonner, op. tit. nos. 203ff.; A. Delatte-Ph.-Derchain, op. cit. nos. 147ff.)
On gem "B." only the uppermost falcon is wearing the crown, but notice what is above its head.
So obviously here these three symbols of the king are not only being associated with the infancy/birth of Horus, but they are also being associated with the appearance of a star.
Everything seems to be lining up so far.
We see the star again with the three falcons in gem "C.", and this time both the uppermost and the middle falcon are wearing crowns, and this time it is the deshret crown of Lower Egypt.
No crowns on the falcons of gem "D.", though nevertheless, like the other animals, they are still well known symbols of kingship, and are still in a triad, and still accompanied by a star. No Lotus this time either.
Gem "E." has all three of the falcons bearing deshret crowns and again we see the star.
In Gem "F." we have some interesting additions. Again we have three deshret crowns making the falcons three symbolic kings, and this time we have Horus surrounded by four stars, and beneath his barque, three stars.
It is conspicuous that we have three stars, again keeping up the significance of the number three here.
Perhaps the four stars surrounding Horus, given their positions, are alluding to the four cardinal points of heaven & earth, East, West, North, and South.
But that much is purely speculation on my part, and that only assumes the four are distinct from the three and not part of a group of seven, perhaps indicating Pleiades or something like that.
Anyway, the point is, here we do have some strong evidence indicting a motif of the infant Horus (Harpocrates) being signified by a star and three "kings" or three symbolic kings.