David McCallum, star of “The Man from UNCLE” and “NCIS,” died in 2023 at age 90. Because his long-standing role as the CBS procedural’s first and longest-serving chief medical examiner Dr. Donald “Ducky” Mallard deserved a worthy goodbye, “NCIS” devoted the entire season 21 episode “The Stories We Leave Behind” to McCallum’s character, with people closest to Ducky gathering to remember their dear friend and mentor. Still, the deep roster of characters and references in the episode has one glaring omission. Ducky’s arguably oldest friend, Leroy Jethro Gibbs (Mark Harmon), doesn’t appear in person to pay his respects.

According to “NCIS” co-showrunner Steven D. Binder, a key reason for omitting Gibbs from the episode was that after Harmon left “NCIS” in 2021, bringing him back for just a quick cameo would be a disservice to the fan-favorite character. Speaking to TV Line, Binder elaborated on this line of thinking:

“Of course the door is always open [for Harmon]. When we bring him back, we’re not going to bring him back for two minutes. It’s got to be something special.”

The tribute episode still features a major cameo, courtesy of Michael Weatherly

What the Ducky tribute episode lacks in Mark Harmon, it makes up with another unexpected return. The end of “The Stories We Leave Behind” features a huge surprise when Michael Weatherly’s Tony DiNozzo — last seen in “NCIS” season 13 — turns up to deliver some touching final words about the dearly departed Dr. Mallard, even throwing in a surprisingly entertaining Ducky imitation for good measure. This, according to Steven D. Binder, made a considerable amount of sense. As the showrunner told TV Line, DiNozzo was a natural choice when they tried to figure out who’d be the best returning character to interact with Ducky’s protégé Jimmy Palmer (Brian Dietzen, who also wrote the episode), who discovers Ducky’s body and shoulders many of the episode’s most mournful moments:

“We gave a lot of thought to who Ducky is connected to most, which on one level would be Gibbs. But it was Jimmy who was there, so it was [about] who Jimmy would connect with, and also bring some levity … and that was Michael Weatherly. It’s really a no-brainer.”

As for Leroy Jethro Gibbs, he might not appear in person but the former Major Case Response Team lead still makes his presence known. After the opening credits, the camera takes care to show Timothy McGee (Sean Murray) opening a letter from Gibbs that contains a heartwarming Polaroid image of the pair and Ducky. Evidently, Gibbs remains firmly in the loop even after retiring to the relative backwoods of Naktok Bay, Alaska.