During an intermission sequence, enable the \camera 1 code to gain control of the player. Type it again when the game gets camera control back. Enable the \give all code if you do not have any weapons, then select a weapon using its bounded key. Enable the /noclip code if you are not in the correct location. Glitching the OSA intermissions with explosives can be very funny. You can even kill Himmler when he is not invincible during the intermission sequence after the defeat of the last Boss. You can find intermissions by loading the auto saves.