Quake 2, Lost Station [Secret Level] (All Secrets Found)

Difficulty: Hard
New weapons: Super Shotgun
New items: Invulnerability
Secrets: 6

Why did I go there? I need really big gun. So, I need Super Shotgun! This two-barrelled baby is quite a handy weapon. Well, it's not so accurate in distance as its fellow brother Shotgun, but in close range this firearm is the king. Nobody can escape two-shells-in-a-row wrath!
Level is quite big and a number of different enemies is also quite large. Anyway, this level isn't too hard as it seems.
Really, this level contains not 6, but 7 secrets. What is the 7th? If you complete the circle in a cart 13 times, an image of rubber duck will appear on the wall behind the cart. I know this Easter egg, but I didn't want to waste your time watching me while I keep riding the cart. It's very boring, so just believe me - there is a secret.
I'm sorry an image sometimes went black. That's bug of the YouTube built-in corrector.
Now, as I have a serious firearm, I can proceed back to the main mission