If the burn had not lasted exactly the correct amount of time, the spacecraft could have ended up in a highly elliptical lunar orbit or even been flung off into space.
ɪf ðə bˈɜːn hæd nˌɑːt lˈæstᵻd ɛɡzˈæktli ðə kɚɹˈɛkt ɐmˈaʊnt ʌv tˈaɪm, ðə spˈeɪskɹæft kˌʊdɐv ˈɛndᵻd ˌʌp ɪn ɐ hˈaɪli ɪlˈɪptɪkəl lˈuːnɚɹ ˈɔːɹbɪt ɔːɹ ˈiːvən bˌɪn flˈʌŋ ˈɔf ˌɪntʊ spˈeɪs.