Metal Gear Solid open world is a vast realm where you can easily miss certain scenes. The following is the list of audio and video events you might have missed.
When you start the game you need to register the date of your birthday. At first, it seems like an unnecessary thing to do, but, actually, it leads to an amazing birthday greetings scene. Do not miss it.
The creator of the series can appear in a scene as a Mother Base special volunteer if his character was saved in Metal Gear Solid 5: Ground Zeroes. After completing missions 4-6 he will randomly show as an s-ranked Intel member. He also can be recruited if you complete the Side-Op 112.
In this installment you can measure your “demon” actions. There is a meter that will change depending on the level of your bad behavior. Such actions include killing or harming animals and people, destroying and crushing helicopters. If you reach a certain level, a cutscene will appear. It will show the shrapnel in Boss’s head assuming the shape of a horn and his face will be covered in a blood coating.
One more secret cutscene can be triggered after the Side-Op in which you need to help a MSF soldier. On the third floor of the Medical Platform a door will lead you to a very familiar girl with amnesia.
A portable shower is a very useful item in your baggage. But if you do not take a shower for a long time, a cutscene of your colleagues reaction will appear. If you are with Quite at the time, an additional video will include her taking the shower with you. Another one of Metal Gear cutscenes with Quite shows her as she jumps out of the helicopter and dances in the rain. You can see it only if your bond level with her in maxed out (the previous scene will help to increase it a lot).
If you like the 80’s music, Metal Gear radio is for you. Traveling on your missions, at times you can hear the cassettes playing the 80’s songs. You can collect the tapes and listen to them at any time during your game. Once you have grabbed a cassette, go to the Mother Base in your iDroid and pick it on a tab near the story tracks. In case you do not like the music of 80‘s you can upload your own playlist to the game. Just go to the folder “CustomSoundtrack” and put the music there.