As experienced rainbow observers can attest, rainbows can appear in half-circles, stretching from horizon to horizon, or any smaller fraction thereof. Despite the superficial appearance of being able to make contact with the ground at both ends, the rainbow possesses an unusual topographic feature: it only has one end. Pots of gold are only ever found at "the end of the rainbow", clearly showing that any given rainbow only possesses one end. Further evidence on the subject states that "we're after the same rainbow's end". I speculate that the superficial appearance of rainbows with two ends is the product of gradual evolution, a natural camoflage to confuse and divert gold-seekers from finding the highly desirable pots.
As we know from earlier work on this subject, it is possible to pass over the top of a rainbow. After all, "somewhere over the rainbow, bluebirds fly. There's a land that I've heard of, once in a lullaby." The data leaves vague whether or not the land is physically located above the rainbow, if one must pass over the top of a rainbow to reach it on the other side, or if, in fact, the observation about bluebirds and rainbows is entirely unconnected with the observation on the land from the lullaby. But it does make clear that rainbows have space above them and, further defining what that space is, a top side. Furthermore, rainbows have a bottom side, a fact demonstrated by the movie title, "Under the Rainbow".
Kermit the Frog once wondered, "Why are there so many songs about rainbows, and what's on the other side?" But which side of the rainbow was he referring to? The end? Above? Below? Or are there, in fact, two more sides to rainbows, this side and that side? A recent e-book's title suggests that there is indeed both a this side and a that side (Dorothy - This Side of the Rainbow), thus bringing to five the number of sides possessed by rainbows. As a sidenote, I suggest that there are not nearly enough songs about rainbows, because I had to resort to non-musical evidence in order to complete my argument.
In conclusion, rainbows have five sides: above, below, this side, that side, and one end. The appearance of a secondary end is only illusion, for while rainbows have nothing to hide, leprechauns do, and have evolved a symbiotic relationship with their respective rainbows which misdirect gold seekers.