My guess is they did this in telecine. I only think this because there are other telecine fx going on such as the overscan/deysync, but most of all they saved the stretch/rotate for the wider shots that could be put anywhere in an edit. I could be wrong.
Clairmont has/had a rig they called the "Squishy Lens", but I don't think it could get this particular distortion. But it would have been easy on DaVinci.
There were a couple distortion lens setups towards the end of the 90s, Clairmont's and the Hylen, but hard to tell which particular one would have been capable of this particular distortion.