Oh god, I struggle to remember most of it because Sage Advice is routinely so bad (and this isn't a 5E thing, it's a D&D thing - it was even worse in 2E, there they often straight up got the rules wrong). There's the classic horror show of "Melee Attack with a Weapon vs Attack with a Melee Weapon", jesus that was bad. There was a ton of bad stuff around targeting spells that just felt anti-imagination 100% MtG card game bollocks. Barkskin can't benefit from a shield was magnificently dumb. Shield Master was some "technically correct, the best kind of correct" idiocy that didn't make the game better.
Honestly after Shield Master I think a lot of people just said "Ok, whatever, that's just like, your opinion man" to Sage Advice in 5E, which had previously been well-regarded.
Here's a truly amazing one that would make most groups overrule the DM if he said something like that:
Can I Revify a killed zombie?