- At the start of the level, turn around and walk towards the tunnel, hugging the left wall, and eventually a portion of the wall will blow up to reveal the secret (be careful not to get hurt).
- Jump on top of the train and walk towards the tunnel. Near the entrance, a secret will trigger and a Riot gun will pop out.
- As you enter the warehouse where you'll obtain the Blue key, look towards the stack of crates to your left. The secret is an open box in the middle of one of the stacks close to the wall. In order to reach it, you'll have to climb some boxes and then jump to another stack, from where you'll be able to jump to it.
- As soon as you enter the Red key warehouse, turn right and go to the wall in front of you. There'll be a crack in the wall to your left. Blow it up to reveal the secret.
- From the last secret, climb the nearby stairs to the higher platform. From there, look to your left to spot another crack in the wall. Blow it up to reveal the secret. Also, there's an alternate entrance to this secret, reached by blowing up some barrels near the entrance to the Yellow key door area. Be careful as blowing up this section causes some extra enemies to spawn in the secret area.
- Beside the conveyor belt (Yellow key room side), open the wall to the right of the belt to reveal the secret.
Level 5: Warehouse\Gallery
|Twin Dragon Levels|
|Level 1: Wang's Home • Level 2: City of Despair • Level 3: Emergency Room • Level 4: Hide and Seek • Level 5: Warehouse • Level 6: Military Research Base • Level 7: Toxic Waste • Level 8: Crazy Train • Level 9: Fishing Village • Level 10: The Garden • Level 11: The Fortress • (Secret Level) Prison Camp • Level 12: The Palace|