I've had several of my cars on chassis dyno(not hub dynos like they used) and engines on engine dyno.
I've never seen one of either type accelerate like that car did on any dyno. I almost think it was not in high gear only, maybe in first gear
All the cars I've dyno tested on a chassis dyno was in high gear starting at what ever RPM I wanted to start the test from and then at WOT up to the highest RPM I wanted, the last one was from 4500 RPM to 7500 RPM on my current bracket car.
I remember hearing the old adage if it doesn't make sense there is usually a reason for it not making sense