Mr. Popper says that he once appeared on The Tonight Show (1953). This is a reference to the fact that Tom Poston, the voice of Mr. Popper, was on the show when Steve Allen hosted it.
Mr. Popper tells Bobby that it takes "great acting, Oscar-caliber" to be a ventriloquist and "to be able to play 2 roles at once." He went on to say "nobody could do it today except maybe Meryl Streep." Coincidentally, she voiced the character of Bill's Aunt Esme Dauterive in the preceding season's Episode 6: "A Beer Can Named Desire."
In addition to a picture of himself with his ventriloquist dummy Chip Block, Mr. Popper also has a poster in his room of Vilma Banky and Rudolph Valentino from the 1926 silent film "The Son of the Sheik."