The edit window has passed so I'll reply to my own comment with a nifty tidbit. The early days of animated films were particularly fun to watch as someone with a background in computer science, as it was a one upmanship competition between the major animation studios (Pixar and Dreamworks) on technology. Monster's Inc had hair. Shrek had a scene with physically-realistic caustic effects of poured milk (really, go watch it--there's an entirely gratuitous scene where a glass of milk is poured to show that they can. milk as a semi-translucent non-homogenous liquid is VERY hard to render as it turns out.) Finding Nemo had lots of water effects, etc.

The challenge of all of this was doing it using rasterization techniques, or integrating more realistic techniques using path tracing into a standard rasterization pipeline in a way that didn't kill performance. But now render farms a big enough and technology has advanced far enough that they can just path-trace everything.