9. A Nuke Goes Off In Valencia - 24
Though 24 first detonated a nuclear bomb in its second season, in that case it was at least exploded in the remote expanse of the Mojave desert, where it would cause an extremely low number of casualties.
But season six seriously upped the ante - or, depending on your viewpoint, jumped the shark - when a smaller-yield nuke was detonated in the Valencia neighbourhood of Santa Clarita, California, causing the deaths of at least 13,000 people.
Even six seasons into 24, it's a totally shocking moment, and yet the show rather oddly downplayed its impact in the episodes that followed, going out of its way to show Californians going about their day like nuclear fallout isn't a thing.
Consider that the attack's body count was more than four-fold the death toll of 9/11 - not counting those who died later - it would've had a tectonic impact on California, the United States, and really the entire world.
And yet, in both the rest of the season and the show as a whole, it's regarded as a triviality. The wider Los Angeles area would've descended into abject chaos and the incident would've impacted global society and politics for decades.