"Can we just say how great the BBC is," Hanks chimed in.
"Now, you're not going to get that live every night in the United States," the actor continued, referring to the wholesomeness of the daily wildlife show.
"That is just something else," Hanks then added, with Willis agreeing: "You're really not, are you?"
The American star has stepped into the role of Colonel Tom Parker – Elvis Presley's manager – for Baz Luhrmann's biopic on the King, simply titled Elvis.