Import a saved game file from Metal Gear Solid 5: Ground Zeroes to get the following rewards.

Gold Bionic Arm; only if the saved game file was created after completing Mission 5 "Over the Fence" and rescuing the Bionic Engineer.
Ground Zeroes Sneaking Suit; available as a special upgrade through the Mother Base.
Hideo Kojima in your crew.
Metal Gear Solid 1 Skin; Snake appears similar to how he was featured in Metal Gear Solid on the original PlayStation version.