Complex sentence: On May 4,1990, Henson made an appearance on "The Arsenio Hall Show", one of his last television appearances, that TV appearance was also Henson's last appearance as Kermit the Frog.
Split into simpler sentences: On May 4,1990, Henson made an appearance on "The Arsenio Hall Show", one of his last television appearances. That TV appearance was also Henson's last appearance as Kermit the Frog.