Okay...

I saw a review of the Incredible Hulk "Duel" rip-off on IMDb, and it mentioned that a later (mid-'80s) episode of "The Fall Guy" used the skateboard chase from "Back to the Future" (1985).

"This is the infamous Incredible Hulk episode written to incorporate footage of Steven Spielberg's Duel. Some sources say Steven stumbled across it while flipping channels and was astonished to see the Hulk driving the monster truck of his 1971 hit TV movie. However, the Hulk never drives the rig in this episode. Spiel must have been thinking about another episode from the first series, '747', which saw the Hulkster trying to land the plane from "Airport 1975". Quite a few episode from the first season made similar use of stock footage from Universal movies; including one that featured several clips from "Earthquake". Although Spielberg made sure none of his movies could ever be used as stock footage again from then on, Universal still managed to recycle the skateboard chase from Spielberg production "Back to the Future" in a mid eighties episode of "The Fall Guy" (with Lee Majors jumping over Biff's car instead of Michael J. Fox)."

I looked through every episode of season 5 (which aired after the movie was released). I couldn't find it. I'm not even sure if that person was telling the truth. (Plus, The Fall Guy was produced by 20th Century Fox, so Universal couldn't've possibly had a say in it.)

However, if someone did see that scene in The Fall Guy, please say so. In the meantime, I doubt this is true.

At one point, CineTel Films started reusing scenes from other productions, like with Scorcher (2002) reusing the tunnel explosion from Daylight (1996), etc.

An episode of JAG used the bus rollover from Universal Soldier (1992).

Worth mentioning: police car shots from The Junkman (1982) were used in the process of assembling the footage for Gone in 60 Seconds 2 (1989).

Also, in the TV series Hardcastle & McCormick, episode "The Crystal Duck", we get a Dodge Aspen rolling over, which then turns into a Plymouth Valiant as it rolls. The Valiant part of the scene was reused from the TV series The Greatest American Hero, episode "Fire Man".

The aforementioned car scene (not that much of a chase, by the way) from 976-Evil 2: The Astral Factor (1991) was also used in Ghoulies IV (1994) and in Kept (2001).

One of the more well-known examples from Phoenician Entertainment: the car chase at the beginning of Ablaze (2001) was actually taken from Striking Distance (1993). If memory serves correctly, Phoenician was also the production company of the aforementioned Gale Force (2002).
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Little Heroes 3 (2002). Can't find this movie anywhere, but according to the trailer, this PM Entertainment distribution reuses the last car chase from PM production Pure Danger (1996).

As weird as it may sound: I just LOVE it when footage is reused, as the makers take a sequence from a totally different script/context and incorporate it into another one. Sometimes, the result is actually good (Running Red; Gale Force; the L.A. Heat series), other times, it'll be somewhat decent (Transformers: Dark of the Moon (the only non-B movie here); The Chaos Factor; The Stray) or, on the contrary, it'll be simply mediocre (Cold Heat; The Big Sweat; American Tigers). You never know.

Here comes a funny one:
Alarm für Cobra 11 - 4x01 "Sonnenkinder", had this Porsche 928 jumping over a bridge. It was reused in one of the second pilot episode for Der Clown. Note: the Porsche had landed on its roof. While Cobra 11 had refilmed the landing with a smaller ramp, Der Clown kept the original crash intact.

This is the funny part:
An episode of Der Clown had a Pontiac Firebird being pushed off a cliff and exploding. Well, Cobra 11 - 9x06 "Liebe bis in den Tod" had a chase with a Maserati Biturbo ending with it falling off a cliff. First, we have a shot of the Biturbo falling, but it was then followed by the footage of Der Clown's Firebird crashing down the cliff and exploding.

The aforementioned Cadillac crash from Quake (1992) was also used in Sorceress (1995) and in Sorceress II: The Temptress (1999).

PM Entertainment started reusing scenes from other films in 1999. Here's a list of the CAR scenes that were reused:

Running Red (1999): MCI bus chase from Red Heat (1988)
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No Tomorrow (1999): Ford Bronco/helicopter chase from Narrow Margin (1990)
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Y2K (1999): Lotus/Mustang chase from Basic Instinct (1992)
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The Stray (2000): Lotus/Diplomat chase from Basic Instinct (1992)
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The Chaos Factor (2000): Mustang/Caprice chase from Species (1995); BMW/Ramcharger chase from Marked for Death (1990)
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Epicenter (2000): Cadillac convertible/Explorer/cable car chase from Metro (1997)
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Con Express (2002): Peterbilt/plane chase from Stop! Or My Mom Will Shoot (1992)

The car chase from 976-Evil 2: The Astral Factor (1991) was reused in Sorceress II: The Temptress (1999) and in Hard As Nails (2001).