You have this level that takes place on a mountain, and the devs wanted to have a spot where you could see the gloomy landscape below with more mountains silhouetted in the distance... except this was the PS2 so it's just two jpegs, one for the sky so you can get some parallax and a curved panoramic one for the landscape. It still looks decent enough 
This era was interesting since you could have pretty detailed character models and environments but still had to use fake backdrops and other tricks for larger environments. Makes you feel like you're on an old movie set
Lol I saw a stage in richard burns rally someone made where they used a very funny old-school method of doing reflections.
They made the "puddle" transparent and just literally mirrored the entire map on the underside of the one you drive on. So when you look at the puddle and see reflections, they aren't reflections, just exact copies of the stuff around you upside down through the map. It looks quite good!
The opening tanker level in MGS2 famously did the same thing. I had the Substance bonus disc where you could view all the 3D models and levels in the game and IIRC you could take the camera under the floor and see the mirrored geometry just hanging around there
This was done quite a bit in older games and I love it. Pretty sure Max Payne 1 and 2 used it extensively.