When the Nazis use the Dora supergun against the landed Race starships in In the Balance. The Race assume the shell arcing miles into the sky towards them must be a missile, so hit it with their equivalent of Patriot counter-missiles... The text then makes an unprecedented cut to a third-person narrator who explains that counter-missile shrapnel works well against thin-skinned missiles... Not so much against solid seven-ton brass shells. And then the Race defenders get a moment of Oh Crap before it hits... Bonus: The ship had most of their nuclear weapons on board.
Actually, not. The ship with the nukes was the second hit. Yes, you've been reading right: Dora managed to shoot twice, and destroy two ships, before being located and destroyed.
Those Wacky Nazis again, specifically Heinrich Jaeger's Panzer Company, when they fight and destroy several Lizard Landcruisers and Fighting Vehicles, considered one of the best small unit battles ever against the Lizards.
One of the raids of Ludmila Gorbunova. She manages to cause a chain reaction explosion during a raid on a Race camp, getting away with minor damage to just her wings.
Just about anything done by Otto Skorzeny, at least until the cruel reminder near the end that we've been rooting for a hardcore Nazi this whole time.
Also, the first time we see him: he enters the Kremlin without papers, browbeats the guards into submission through sheer ballsiness, and he's doing all of this wearing his SS uniform in the very middle of Moscow. By this very scene you may understand why you forget he's an hardcore Nazi until he tries to nuke Lodz under pretense of helping the Jewish resistance to take over the city.
When Stalin sets off the first human-built nuclear bomb, annihilating a significant fraction of the Lizard armed forces. (Later, when humans and Lizards start taking turns nuking each other's cities, it gets a lot darker. But that first human-built nuke is awesome.)
The moment in Homeward Bound when the crew of the Admiral Peary learn the Commodore Perry took five weeks to travel from Earth to Home.
During the Race invasion of Britain, the RAF duped the killercraft pilots into wasting dozens of missiles by using older aircrafts transformed into early remote-controlled drones. As soon as the missiles were exhausted, the actual fighters, comprising the Spitfires, the Hurricanes, the Mosquitoes, and the Gloster Meteors (Britain's first jet-powered combat aircraft), would engage their cargo aircrafts, forcing the killercrafts to engage in a battle at such low speeds that the RAF fighters had the manouverability advantage.
One for the Japanese Imperial Troops in China: they managed to shoot down a killercraft using massed fire from bolt-action rifles, hitting both engines.