Deathstroke's Mask is seen multiple times in island flashbacks, and Deathstroke wears a new version of the mask when he returns to Starling City. The original island mask is made out of a cloth material, while the new mask is more metallic.
Also, when Slade recruits an army in season 2 he gives his soldiers masks, very similar to his own.
Batman: Arkham Origins
Slade bears a blue and orange mask in the video game Batman: Arkham Origins. This mask appears to have a latex coating on the outside, and is made of some type of metal or other hard material.
Injustice: Gods Among Us
A different version of the mask also appears in the video game "Injustice: Gods Among Us". This mask features a red robotic eye, not unlike the New 52 version of Slade.
Mortal Kombat vs. DC Universe
Slade wears a slightly different version of the mask in another video game, "Mortal Kombat vs. DC Universe".
Deathstroke wears a blue and orange mask with a robotic red eye in the New 52. The mask can also flip up, revealing Slade's face.