I'm glad you said this was Sgt Bilko because any relationship of this sequence to the 50's TV show is absent.As a point of interest, if a hover tank fired a high velocity round wouldn't the recoil move it backwards?
I do like Dan Akroyd. Blues |Brothers is one of my fave films of all time. I remember watching Phil Silvers as the original Bilko in the 60's. A very funny show. As to recoiling Hover Tanks, you may well be right Terran. Is it friction that reduces recoil on normal land tanks?
I don't know the science of it but the sheer weight of a tank keeps it grounded. If you've seen any field gun being fired to rolls/jumps back from recoil.