BATMETAL - All hidden clues for the door code

If you haven't seen Batmetal yet, i recommend you do so in advance (only 3 short videos). Links are further down.
At the end of "Batmetal Forever", released on April 1st 2018, we saw the list of clues / easter eggs that were hidden throughout the Batmetal trilogy. Even more amazing is, that the first Batmetal Video was released back in 2014!

In this video, i wanna show you all those hidden easter eggs.

[Original Videos]

• Batmetal
• Batmetal Returns
• Batmetal Forever

[Music]

• Intro / Outro: Halvorsen - Wouldnt Change It [NCS Release]
• Part 1 (Batmetal Forever): Awaken - Metalocalypse (The Dethalbum)
• Part 2 (Batmetal): Face Fisted - Metalocalypse (The Dethalbum)
• Part 3 (Batmetal Returns): Murmaider - Metalocalypse (The Dethalbum)
• Transitions: Detharmonic - Metalocalypse (The Dethalbum)