Stabbing the Grenade Launcher wielding soldier on the left.
Taking the Ray Gun.
The end of the level.
After level 5, the Marine will now go to level 6 where there is a prison with 2 Civil Security Lites who will be the player's allies after the Marine frees them, until the end of the Level. The Marine and his allies make their way down a gravitator shaft onto a grassy area filled with hostiles.
A crashed ship can be found near the end of the level at the bottom, with Grenades, a Rocket Launcher and a Ray Gun on top of it, which can be picked up by the player. The player then must make their way to the landing next to the gravitator area and complete the level.
If the player completes the level with one or both of the Civil Security Lite allies still alive, they will not reappear in level 7 or any other level of the campaign.
There has been speculation regarding the fate of the allies. It is possible that they were killed or recaptured after the Marine's escape, or managed to stay alive by killing their adversaries or escaping in a similar fashion as the Marine.
If you kill those prisoned CS Lites via the Ray Gun (or any other weapon which can shoot through thin walls) and break a part of their bodies and then press the button to release them, that broken part will grow back and change rapidly.
Who gave him a gun?!
Sometimes a weapon may glitch inside a prison cell. This tend to happen after killing prison guards via explosive weapons. This doesn't lead to any significant gameplay changes, though.