"Dancing With the Stars" celebrated its 20th anniversary with a special episode featuring celebrity guests, including a surprise virtual appearance by Prince William, who wished conservationist Robert Irwin and his partner Witney Carson good luck.Irwin earned the season's first perfect score with a foxtrot dedicated to his late father, Steve Irwin, and later received another perfect score, impressing judges with his enthusiasm.Meanwhile, Tori Spelling expressed concerns about Irwin having an unfair advantage due to the emotional moment shared with his father during performances.