Although data files for a jetpack were present in the game, the vehicle itself was later scrapped from the game for unknown reasons.

A mysterious mural inside the tramway station atop Mount Chiliad includes a drawing of what appears to be a jetpack, leading to speculation that such a device might be hidden somewhere on the map, though it was later revealed that it was an unimplemented idea from the game developers.

Another UFO, presumed to be a mock-up, though it makes similar sounds to the 'real' UFOs, can be seen embedded in the roof of Bishop's WTF?! on Vinewood Boulevard.

Unlike the previously mentioned UFOs, this is the only 'real' one that the player can see without having to 100% complete the game.

A third UFO, the same model as the previous two, though without the 'FIB' markings, is located underwater, north of Paleto Bay and Procopio Beach, covered in plants.

This UFO can only be seen at 3AM in stormy weather.

A second UFO with 'FIB' markings appears above Mount Chiliad.

This craft appears to have ' FIB' written on the side, a likely reference to the conspiracy theory of government surveillance.

Another UFO appears above the Beam Me Up area in Sandy Shores.

From 3AM to 4AM, a spinning green light will be projected on top of one of the fort's buildings, marking the UFO's location. On the bottom of the ship, an unknown device can be seen rotating around. Segregate being an anagram, when rearranged, it spells out 'easter egg'. The words 'segregate and rearrange' are written on the side.

One of the UFOs appears above Fort Zancudo.

Three appear in the sky and one appears underwater.

Multiple UFOs can be seen, most of them only after 100% Completion is obtained.

There is a wrecked pickup truck bed in Stab City with a real-life California license plate.

This references a longstanding myth involving Grand Theft Auto: San Andreas and also foreshadows the post-game mission The Last One. Shooting it does nothing and it abruptly disappears after a few seconds. If the player zooms in on the thermal heat dot on the bottom right, it appears to be Bigfoot standing still.

In the mission Predator, Michael must use a sniper rifle fitted with a thermal scope to find the O'Neil brothers in the woods at night.

The alien frozen in ice under the bridge in Ludendorff, North Yankton.

Additionally, the player may also see this same secret during the mission Bury the Hatchet.

The player is able to drive down an embankment and onto the ice.

In Ludendorff, North Yankton, underneath the train bridge the gang passes in Prologue, there is a frozen creek.

6 References to real life people and events.

Hitman 2 easter eggs