The Sentinel and the Scorpion are fictional shoulder fired, reloadable, multi-launch rocket systems. The Sentinel can be fired in either unguided or TV-guided modes, while the Scorpion replaces the TV-guided mode with heat-seeking. The Scorpion is also available as a fixed weapon on some multiplayer weapon sets.
Both weapons use the same model. Drake uses one of those models in the last level, when you vs him.
The M202 FLASH appears in the game as the "AT-420 Sentinel", though there are a few inaccuracies. It is incorrectly depicted as firing laser guided missiles. The four shot clip is shown extending from the front of the weapon instead of from the rear, there are no grips or sights, and there is only one hinged cover in the front (there should be a second one in the back to act as a stock).