Also one of the very few movies that Led Zeppelin have allowed to feature one of their songs.
When the Gorgonites decide to start fighting back. Especially when the Commandos realise how screwed they are before the counter-attack actually begins.
Alan's mother is trying to deflect the flaming tennis balls the Commandos are firing into the living room. When one nearly hits the family cat, she goes "That's it!" and knocks the next right back out at the Commandos, causing a nice little explosion.