There's a surprising amount of coasters that run backwards nowadays! You have a handful of wooden coasters that generally run (or did run) backwards as part of a Halloween event (Racer 75, Thunder Road (RIP), Racer at Kings Island and Viper at Six Flags Great America) but a lot of modern steel coasters actually do it by design. Like Hagrid's Magical Creatures Motorbike Adventure at Islands of Adventure in Orlando has a decently lengthy backwards section (plus some other surprises I won't spoil) or Mr Freeze at both Six Flags Over Texas or Six Flags St Louis both go through their courses both forwards and back. And that's not even counting Boomerangs like Bat at Canada's Wonderland that another sibling commenter mentioned

(PS glad to see my favorite hobby being mentioned on HN, I could literally talk about this stuff all day)