GTA 5 Secrets and Easter Eggs: UFOs, the Mount Gordo Ghost, Bigfoot and More

Short answer: GTA 5’s best secrets are the three UFOs that appear after 100% completion, the ghost on Mount Gordo between 23:00 and midnight, Bigfoot in the mission “Predator”, a frozen alien in the prologue and a crashed UFO on the sea floor. Each one is listed below with where to look and what you need.

The UFOs and the Mount Chiliad mystery

Three UFOs appear in Story Mode only after you reach 100% completion. They cannot be interacted with.

Mount Chiliad: above the summit, in stormy weather in the early morning hours.
Fort Zancudo: a cloaked UFO hovering over the military base.
Sandy Shores: over the Sandy Shores area.

The mural inside the cable car station at the top of Mount Chiliad started the hunt. It shows a UFO, a jetpack, an egg and an eye joined by lines. The egg stands for 100% completion and points to the UFO over Chiliad. The jetpack refers to a feature that later arrived in GTA Online’s Doomsday Heist, not to anything in Story Mode.

The Mount Gordo ghost

Go to the north-eastern cliffs at the top of Mount Gordo between 23:00 and 00:00 in-game time. The ghost of Jolene Cranley-Evans floats above a bloodstained message reading “Jock”, the name of the husband who killed her. She vanishes if you walk up to her, so stay back and use a weapon’s sights or first-person view to see her clearly.

Bigfoot

In “Predator”: as Michael, sniping from the helicopter with thermal vision, look at the lower-right heat signature among the O’Neil brothers in the woods. It is Bigfoot, and it disappears after a few seconds.
Playing as Bigfoot: reach 100% completion, finish Franklin’s mission “The Last One” and eat all 27 peyote plants. Golden peyotes then appear, one per weekday, between 5:30 and 8:00 in snow or fog. Eating one turns you into Bigfoot. Our GTA 5 collectibles guide covers the peyote plants.

More secrets and easter eggs

Secret	Where and how
Frozen alien	In the prologue, drive down the right side of the hill towards the train tracks, cross the frozen river to the area under the bridge and look under the ice. Be quick, or the mission fails.
Underwater UFO	A crashed UFO on the sea floor at the northern edge of the map. You need a submarine.
Los Santos Sea Beast	A giant skeleton underwater off the eastern edge of the map.
A case with $25,000	A random event in Mount Chiliad State Wilderness, north-east of the highway bridge: four crashed cars and bodies, a nod to No Country for Old Men. Walk down the hill past the cars to find the case.
Giant snowman	A cold storage building in La Mesa. Find the door that is slightly open and shoot away the boxes.
The JB 700 (James Bond’s Aston Martin)	For sale on the Legendary Motorsport website after Michael’s mission “Deep Inside”.
Red Dead book	A blue book called “Red Dead” by J. Marston on the shelf in Franklin’s Vinewood Hills house.
1.21 gigawatts	A sticker on the circuit box of the satellite tower in Sandy Shores, a Back to the Future reference.