[Basssiiie]

The spot lights and the cranes are probably spawned by SA-MP itself, instead of by the game via the IPL lists. (As they can move, in Singleplayer, at least.)

Main.scm can be found in GTA San Andreas/data/script/, you can decompile it using something like Sanny Builder. Don't be afraid of the 500.000 lines of code that's in there.