Yes. No speedos went over 85 mph at the time. "I can't drive 55"... gas crisis era and the government at the time thought that if the car didn't show speeds over 85 mph, then people wouldn't drive so fast and the vehicles would be better on gas.
Back to the Future used all kinds of movie magic for that sort of thing. The speedos got fudged... like an artist painted over the real numbers and shuffled the markings so it went higher and could show 88 mph. Watch closely to the mall chase scene when they show the speedo. Three times it is shown and you'll notice the odometer there too. It jumps around... 32,065 or something like that, then 31,950 and then back to 32,070. It took them more than one take to get it right and so spliced the footage together.
Not so sure Bob Gale and Robert Zemekis counted on people watching the movies 100 times on Bluray and being able to scrutinize the tiny details.
Marty bonks his head on the steering wheel at the end of the first movie as he is trying to get the stalled car to start when he's at the starting point on the road leading to the clock tower... and the horn goes off just as he does this? The horn button isn't in the steering wheel centre pad, it's on the turn signal stalk. You push it in to honk the horn.
Or the door pull straps... those were loose add-ons for the first 4,000 cars made and then built into the arm rest on the 5,000 or so cars after that. I think the engineers just forgot not everyone's arms are as long as JZD's were. The movie cars had the loose style. And in that mall scene where Doc is explaining how the car works, you can see the pull strap on the driver's door in three different ways. First time it's connected correctly, second scene it isn't there at all, and the third time it's tied in a knot instead of using the hoop. I figure Christopher Lloyd kept bumping into it in that scene and so had them remove it and then they forgot to put it back on the same way.
Tons of stuff like that. DeLorean stuff was hobby #1 until pinball came along. Now back to our regularly scheduled programming...