During early concept stages of the game, Hanzo and Genji were once originally the same character, a cyborg ninja named Hanzo that wielded both a sword and bow. As time went on, Hanzo was split into two characters, with Hanzo using the bow and arrows, and Genji who was given the cyborg ninja motif and sword.
The two songs that Lúcio plays during his Crossfade ability have been officially released by Blizzard onto Soundcloud under the album name "Synaesthesia Auditiva". The speed-boost track is called "We Move Together As One" and the healing track is called "Rejuvenescência".
The coffee shop in Eichenwalde lists "Kosakezipfel" on its menu. This is a reference to Loriot, a German comedian. "Kosakenzipfel" is a fictional dessert that originates from one of his skits and roughly translates to "Cossack's Cusp".
During Overwatch's beta, a pose for Tracer was removed after some beta testers deemed it to be too needlessly sexualized. The pose which replaced it is an homage to a work by Alberto Vargas, a pin-up artist.
D.Va's first design could be seen on a wall piece at one of Blizzard's events. Since every other character on the piece sports their final designs, this would suggest D.Va was one of the last characters from the original roster to be finalized.
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In the escort level Route 66 during the game's beta, there were magazines featuring the characters Symmetra and Mercy littered inside the outhouse, suggesting that members of the Deadlock Gang who reside there masturbate to them. The magazines were later removed in a beta patch.
In the Overwatch Cinematic Trailer, a security guard can be seen playing Hearthstone on a tablet device.
Overwatch was born from the remnants of Titan, a sci-fi MMO Blizzard had been working on for years but ended up cancelling.