dˈʊɹɹɪŋ ðɛɹ tɹˈɛk hˈoʊm, ðɪ ɛksˈɛlsjɚ kɹˈuː ɛŋkˈaʊntɚ mˈɪɹɚ jˈuːnɪvˌɜːs vˌɛɹɪˈeɪʃənz ʌvðɪ ɚɹˈɪdʒɪnəl sˈɪɹiz mˈɪʃənz, ɪŋklˈuːdɪŋ ðɪ ˈɛm fˈaɪv mˌʌltɪtɹˈɑːnɪk kəmpjˈuːɾɚ ðɪ ˈʌltᵻmət kəmpjˈuːɾɚ, bˈælɑːk ðə kˈɔːɹbəmˌaɪt mənˈuːvɚ, ðə dʒˈaɪənt spˈeɪs ɐmˈiːbə ðɪ ɪmjˈuːnᵻɾi sˈɪndɹoʊm, ænd ðə plˈænɪt kˈɪlɚ ðə dˈuːmsdeɪ məʃˈiːn.
During their trek home, the Excelsior crew encounter mirror universe variations of the original series' missions, including the M5 multitronic computer (The Ultimate Computer), Balok (The Corbomite Maneuver), the giant space amoeba (The Immunity Syndrome), and the Planet Killer (The Doomsday Machine).