I slow cooked a pork roast for 8 hours, but when I sliced it, I saw this weird shiny green and rainbow reflection on the meat fibers. It looks like gasoline on water. Did the meat go bad?

11. When in Doubt: Follow Basic Food Safety Rules
Always cook pork to an internal temperature of at least 145°F (63°C) with a three-minute rest. Practice good kitchen hygiene, wash hands and surfaces thoroughly, and refrigerate leftovers promptly.

If you are ever uncertain about the safety of meat, it is best to discard it. When it comes to food safety, caution is always the wiser choice.