Roddy McDowall and
Kim Hunter were appearing to promote the third of the "Apes" films,
Escape from the Planet of the Apes (1971), which had its New York and Los Angeles premieres within the preceding few days and would have its UK premiere about a month later. One of their co-stars in the movie,
Ricardo Montalban, had appeared on Carson the preceding February (
Episode dated 16 February 1971 (1971)), although that was likely to promote his role in the pilot of the new
George Kennedy series
Sarge (1971), titled
The Badge or the Cross (1971), which would air in the week after Montalban's "Tonight" appearance.