Bruno Mars

In this video, Bruno is seen playing his Roland Juno-106 at about 3:30 for the fast brass synth used in his single 24K Magic. A Roland Juno-60 is also noticeable by its white momentary/toggle button in the left side, just in front of the Roland Juno-106.

Bruno can be seen using this Moog at :49 of the video linked above. He shows to reporter Lara Logan as regards as his brand new single and title-track 24K Magic. He uses it for the bassline of the song, in fact.

At the beginning of this video, Bruno Mars can be seen playing a Korg SV-1 Stage Piano.

Mentioned on the official product page.

The M4000D digital Mellotron has been very well received by the keyboard community. It has been used onstage and in the studio by many well-known artists, musicians and producers, to name a few: FooFighters, Red Hot Chili Peppers, Smashing Pumpkins, Wilco, Incubus, Queens of the Stone Age, Eels, Jackson Browne, Bruno Mars, Band of Horses, Fleet Foxes, Sean Lennon, Brendan Benson, Air, Kooks, Train, Elbow, Michael Beinhorn, Bob Rock, Raphael Saadiq, Noel Gallagher, Gotye��

He is seen with it here

It can be seen at 0:40

He is seen playing it live here

the synth on the right in the prologue (check the shape and where the red lights are)

Bruno Mars uses the Yamaha Montage 8 keyboard, as evidenced by a live performance captured on video during his "Die With A Smile" concert in Jakarta and Las Vegas with Lady Gaga playing on it. In the video, the branding of the keyboard is obscured, but the instrument is identifiable.