When Dr. DeBryn returns from his fishing holiday, only to be collected by Morse for immediate police duties, he is crisply told, "You're needed!", a variant on the line (more usually, "We're needed!") used by Steed and Emma Peel as a catch-phrase at the start of each episode in the first color series of "The Avengers" - which appeared during the period depicted in this "Endeavour" story.
Similar (identical?) quotes. As Craven is surprised by the tiger having circled around behind him, Craven echoes Muldoon's reaction to finding a Velociraptor unexpectedly behind him.