Which Godzilla movie was this scene in?

Godzilla vs. Megalon (1973), directed by Jun Fukuda. Generally considered one of the worst entries in the series, but is also one of the most seen Godzilla films in North America. It has a pretty big cult following.

I suspect the dropkick is one of the more apparent reasons why it has a cult following.

I mean, current Godzilla iterations are big, and strong, and do different things, bu have any of them had the power to defy physics so beautifully, so gracefully? :P

^True. But mostly I think it has a lot to do with how the Baby Boomers recall it thanks to the NBC primetime showing in 1976. (The one with John Belushi hosting in a Godzilla costume.) The film got the widest audience in North America for a Godzilla movie and left viewers believing every Godzilla film was like this one.

So while people like my parents and their peers think back to this movie when they think of Godzilla, there are also some post-MST3K folks who either recall or look up legendary schlock to embrace as a cult phenomenon. Godzilla vs. Megalon is unfortunately one of those films.