The Master Chief Collection is... different?

I had heard plenty of people online complain about The Master Chief Collection, but I didn’t realise just how glitchy it was. I was playing a bit yesterday and decided I’d see how quickly I could race through the 343 Guilty Spark level, but no matter what Campaign options I chose I never got what I wanted. When I chose classic graphics with classic music I got the new graphics with the new soundtrack. When I chose the new graphics with new music I got the old graphics with the old soundtrack. Whether I chose scoring, timing, competitive scoring or competitive timing I got either nothing at all or I got one of the other options. It was rarely what I had actually chosen.
The same thing started happening today, but then it got weirder. I eventually decided to try a playlist. I chose the Final Four (or whatever it’s called) playlist where you play through the final level of each Halo title. It should have been in Normal difficulty. Now I’ve played Halo for a good thirteen/fourteen years now. I’ve played many times in all four difficulty settings; more times than I could hope to count. When I chose the playlist it said the difficulty was set to Normal. As I was playing I’d pause to check the difficulty. It still came up Normal. … Except it wasn’t. There is no way I was actually playing Normal difficulty. I know Heroic when I see it. That was Heroic alright.
What’s more, when I began this playlist it randomly gave me Competitive Scoring, which this time I hadn’t actually chosen. There were a bunch of random little things that came up as well that were just plain weird. I still own Halo 2 on the original Xbox. I got it soon after its release and have played it pretty much all the way up until I got The Master Chief Collection just recently, so I know what to expect when I’m playing each level. On The Great Journey the first door you’re supposed to enter wouldn’t open for me in The Master Chief Collection. I had to revert to the last checkpoint and got through the second time. Maybe there was a reason for that. I hadn’t killed all the enemies, but it’s not something I remember from the original. What’s more in the original when I released the Hunters from behind their shield doors they would rescue the Elites, but nope. After fighting the Brutes they just stood there staring at the Elites stuck in their cells.
There were plenty of weird little things like this. I forget them all now, but I swear even the physics have changed slightly. Especially when it comes to the Warthog. …Speaking of the Warthog I was doing the final Warthog run on The Maw and I swear there were a lot more random explosions, or at least they were actually harmful explosions from the ship whereas in the original they were more just for the atmosphere. Maybe I’m imagining the extra explosions, but I definitely died from one. After making my way through these explosions I died running on foot to the Longsword. The thing is I should have respawned in that elevator at the start of the countdown timer, but I didn’t. I spawned shortly before the large trench jump. I played this level a lot on the original Xbox and this never happened once.
So my question is what other particularly weird issued have you had with The Master Chief Collection? Issues that weren’t in the original games?

I might also take this moment to mention to 343i that I’m unable to watch the Spartan Ops cinematics at all, and anything I try to watch on the Halo Channel either doesn’t load or looks like it’s in 240p. I’d appreciate it if it got fixed.