Dickinson's poems are deliciously deceptive in their apparent simplicity. When read aloud, this poem, like many of her others, seems effortlessly consistent and delightfully smooth. However, upon closer inspection, we can see some of the craftier, odder quirks that make her verse so unique.
In particular, we'd like to draw your attention to some of the funky rhymes she employs in "I like to see it lap the Miles." You may not notice them when you read the poem out loud – after all, we want a poem (especially one written in sing-songy ballad meter, like this one) to rhyme perfectly, so we will often unwittingly force it to do so. Still, if you really look at Dickinson's rhyming words, you'll notice that they don't always exactly…well, rhyme.
For example, how about "up" and "step"? Though these monosyllabic words look alike and sound kind of alike, they aren't perfect rhymes. Or in the second stanza, what about "peer" and "pare"? Again, they're deceptively similar – but they don't quite line up. Similarly, "while" and "hill," and "star" and "door."
All of these would-be rhymes share consonant sounds, but not vowels, and so offer the illusion of perfect rhyme to the reading eye, but not necessarily to the reading mouth. These are all examples of slant rhyme (otherwise known as "half rhyme"), a cool poetic device that allows the poet to use words that have consonance (alliteration of consonants) as mates in a rhyme scheme.
Slant rhyme in Dickinson's poems contributes to the sense of depth and ambiguity that her deceptively simple and elegant poems possess. Here, we can see how the slightly odd, somewhat off rhymes add a little quirkiness and playful life to the otherwise consistent and predictable rhythm of this poem. This little trick of the eye and ear adds to the ambiguity of the poem's meaning, so that we know that the poet means us to question what meets the eye. Take our word for it, there's always more to Dickinson than meets the eye.