The game GTA San Andreas was the last major 3D GTA game of the PS2 era. It was the first one to introduce a flyby mechanic, whereby planes, identical to the ones pilotable by the player, and flown by in-game AI, would periodically fly over as an environmental detail. However, due to many different reasons mentioned throughout the video, these planes would often unexpectedly crash into obstacles, sometimes exploding right next to the player. Many attempts were made during the game's development to eliminate these plane crashes, but due to the complexity of the map, the PS2's hardware limitations, oversights and limited development time, the issue made its way onto the final game.
Personally, I find it really cool that something this relatively minor feature in a 20-year-old is being broken down in such detail in this fashion.