Suspended Pelican

It is possible to see a Pelican dropship suspended in mid-air on the level, Metropolis.

Directions
Play through the Metropolis level until two Pelican dropships arrive, this is right before you meet Corporal Perez. The Pelican with the attached Scorpion Tank will fly above the building and freeze in place. If you shoot rockets, Wraith plasma mortars or Scorpion shells at the Pelican (with the Sputnik skull) until it moves about 50 ft and then go up the staircases, the marines (and Sergeant Banks) and the Scorpion won't be there. The Scarab will still briefly pause, but it won't shoot at where the tank used to be.

Also, if you fire at the Scorpion Tank with the Wraith mortar, Gauss Warthog or Rocket launcher, you can destroy it.