Located in Staunton Island is a sign reading "You were not supposed to be here you know". It is located near Donald Love's mission location in a west direction. In the car park, Claude would need a large vehicle to get over a wall. Following the small path behind the wall will lead to the sign and a conveniently placed exit ramp. The car park is also the setting for the mission Kingdom Come for King Courtney. It is also seen in Liberty City Stories.
 Ghost Town
Using the Dodo, fly Claude behind the most northerly mountains of Shoreside Vale and a town will appear. On the PC, there is a modification that is a bridge connecting Shoreside Vale with the ghost town. The town is used for the beginning of the game in the bank heist and where Claude is left for dead. The town is not solid. Near to the town, still flying, the developer's names also appear as towns.
 Obscene Egg
The obscene egg can be viewed from the little river across from The Malibu Club and looking to the large building in the east. It starts at 23:00 for one minute. Lights from the building switch on, and the outline resembles male genitals. Water spurts from the top every 15 seconds.
 An Easter egg that's an Easter egg
This easter egg is literally an easter egg! It can be seen by going to the west island and to the beginning of the bridge to Prawn Island. just to the north is an eneterable building with VCN written on it. Enter it from the south side and Tommy will be near a helipad. Going up the ramp (there's a hidden package visible next to it) to the helipad and face the building next door. Jump into the window closest to the helipad and there is the Easter egg. The same egg can be viewed in the Playstation 2 version of Grand Theft Auto: Vice City Stories.
 Ghost Tower
San Andreas is a large state, meaning more Easter eggs.
 Easter egg that isn't an Easter egg
This Easter egg can be seen on top of Gant Bridge in San Fierro it can be accessed at an time, as long as CJ has access to San Fierro and a jet pack. While on the jetpack, fly CJ to the top closest to San Fierro and the sign is visible.
Zombotech is also located in San Fierro and is likely a reference to the Umbrella Corporation. There is even a site dedicated to the fictional company, claiming to be related to the Umbrella Corporation. There are elevators going up to the various zombie facilities, although they are non-accessable. In the middle of the building, there is a large model of DNA going all the way to the top.
In order to keep up with the realism of the game, there is only one easter egg, located in The Statue of Happiness.
 Heart of Liberty City
The heart can be accessed by stealing a helicopter (or otherwise somehow obtain one) and going to the Statue of Happiness. Jump out when the helicopter is right next to the base of the statue and enter one of the doors. Climb up the ladder to the heart, which is restrained by chains.
 See Also
Related ThreadsComplete List of Easter Eggs/Secrets !!!CONTAINS SPOILERS!!! - last post @ Jan 27, 2014
Easter eggs - last post by @ Feb 6, 2008
Easter Eggs (complete List) - last post @ Aug 24, 2014
Easter Egg Exploration Team [Possible Spoliers] - last post by @ Nov 30, 2004
GTA V Easter Eggs Compilation - last post by @ Sep 23, 2013