"Ten Little Indians"

I listened to the 1990s single-CD re-issue of Surfin' Safari and Surfin' U.S.A. (with bonus tracks) to-day, and I noticed a small thing about "Ten Little Indians."  At first, I noticed only that the "waterfall" in the line "The fifth little Indian took her down the waterfall" is pronounced with an extra syllable and that that extra syllable is lower than the rest, musically representing that fall, but when I figured out the specific notes, I discovered that the whole word descends.  The four syllables are sung to the notes B B G# E.