Enter a Scarab glitch

Get inside the Scarab in The Great Journey is a glitch in which you can get on board the Scarab before the cutscene Backseat Driver. When you get to the platform, grenade jump to one of the legs. Then crouch jump onto the deck. You can now go inside the Scarab (there is no shield), and push the invincible Johnson to the edge of the Scarab, and get him to fall off the Scarabs deck, and down to the sand far below.

Warning: This requires timing.

When Johnson jumps aboard it for the first time, before that, you must bunny hop to the edge of the platform. When you get there, jump. It is extremely important that you time this perfectly. As the Scarab moves back a bit, jump right then. You should end up going higher than usual. This can take a few attempts. If it works, you must jump towards either the left or right leg. If done correctly, you will land on the leg. Then crouch jump onto the deck.

Note: Pushing Johnson over the edge will stop the cutscene. Do not attempt this unless you want to revert to the previous checkpoint, or have already beat the game.

There is another way to do it. First you need to activate the Sputnik skull, then go to the level The Great Journey, go to the part where two Wraiths come to keep you out of the structure. To your right is the rock that hid the closer Wraith from view.

One other way of doing it is have the sputnik skull on and to hi-jack a ghost and drive it so that it is on the side of the scarab that is nearest to you when you first see it. Then you must get out of the ghost and place a grenade next to the ghost, but NOT on it as this will cause you to die, and then get back in your ghost and the explosion should hopefully take you up to the platform, from which you can get in the scarab.

Note: It is impossible to drive the scarab, all you can do is look around.