UFO

In GTA San Andreas, there are small blinking lights that can be witnessed flying at a very high altitude at any time of the day. These blinking lights fly faster than any vehicle in the game, and they have a very long vapor trail behind them. The player can never catch them, as they fly very fast. The purpose of these lights in the game has been a very hotly debated subject within the GTA Community.

In GTA San Andreas, the blinking lights in the sky could have been designed by game developers to look like airplanes. However, it is still unknown if game developers wanted these lights to look like UFOs. The only reason players think that they are UFOs is probably because they can never catch them. If the player gets close enough to the strange lights, he will find that they are just unsolid glowing spheres.

In GTA San Andreas, there is a UFO map of San Andreas inside the Lil' Probe Inn, which appears to be marked with small pins in various places on the map. The map appears to be marking UFO sightings within the state. Interestingly, the same map can also be found inside Mike Toreno's Ranch and in Area 69. An NPC known as Mr. Trenchcoat is compared with UFOs. He will talk to CJ about them and will talk to other peds about aliens as well. 

Snapshot icons usually get confused with UFOs, because at night, the icons emit a bright glowing light so the player can locate them easily. One example is the Snapshot icon hovering over Missionary Hill in San Fierro. However, most of the UFOs that have been seen look exactly like these glowing icons.

Nevertheless, it is not known why these strange blinking lights are included within the game, because the game features real solid airplanes that fly regularly over the sky.