DaveWatch: Countdown to Letterman's Last 'Late Show,' Day 20

The host stays in pleasant chat mode, Downey Jr. stays put and Elvis Costello trots out an oldie but a goodie

Robert Downey Jr. on the 'Late Show with David Letterman.' Credit: Jeffrey R. Staab/CBS

Maybe it was just the excitement of "Bring Your Daughter To Work Day" — or, as Dave willfully misconstrued it, "Bring Your Otter to Work Day" — but the overall energy level of last night's episode of the Late Show was up considerably from that of the previous one. Then again, when you've got the combined manic energies of Robert Downey, Jr. and sports commentator Chris "Mad Dog" Russo rebounding off the walls of the green room, some of it's bound to eventually rub off on the host.

Downey, dropping by to promote Avengers: Age of Ultron, mugged, preened and cracked wise, while Dave enthusiastically served as his straight man. There was a flash of the old prankish Letterman when, setting up a clip of the new superheroes-versus-evil-robot blockbuster, he cut to a clip of an old B&W 1940s serial in which a man in a clunky metal suit waved away bullets. ("I was not expecting that," Downey deadpanned.) Unlike in his recent interview with Britain's Channel 4, the star stayed put the whole time; of course, Dave didn't ask anything more personal than a couple of questions about his kids and what he did for his 50th birthday. (Answer: Hired Duran Duran and Steely Dan to play for him and his friends at an airplane hanger. As one does.)

Russo announced that he'd been a guest on Letterman over 30 times, dating back to 1991 — a revelation which made one wonder just what kind of blackmail the sports personality has been holding over Late Show producers all these years. Russo's insufferable Jerry Lewis-style braying made his guest segment feel longer than an extra-innings ballgame with a couple of rain delays thrown in, but Dave seemed to be genuinely enjoying their chat. Hey, it's the man's last month on the tube; and if he just wants to engage in casual pleasantries with familiar faces, well, you can't say he hasn't earned the right.

The show has been trotting out its share of flashbacks in its last month, and last night's oldie-but-goodie rewound things to 1995, in which Dave tooled around L.A. in an old convertible, filling it with tacos and using a hydraulic lift in a muffler shop to make it crush pumpkins, eggs and other squishables. While it might not have been a truly classic "old Letterman" bit, it was still fun to be reminded that there once was a time when Dave would attempt to prank a tow truck guy by pretending to lick oil (actually chocolate syrup) off a car's dipstick.

Elvis Costello — making his 27th appearance on the show — chose to play Dave off with his old running buddy Nick Lowe's Rockpile song "When I Write the Book," with lyrics bidding a wry farewell to the vigor and ambition of youth. It could have been construed as harsh under the circumstances; thanks to Costello's warm rendition, it came off like a knowing nod from one aging and influential artist to another. They might be "just the shadow of the boys they used to be," but at least they're still here. And last night, that indeed felt like something to be thankful for.