The untitled drama about sexual obsession and betrayal featuring two intersecting love triangles is currently filming in Austin, Texas and stars Ryan, Rooney Mara, Christian Bale, Natalie Portman and Cate Blanchett.
Now a grainy, black and white picture has emerged on the internet showing Shame star Michael filming a street scene with Canadian hunk Ryan.
Members of the public also wrote on Twitter that they had seen the pair filming together in Austin.
It is not know if Fassbender's scenes will make the final cut.
Holly Hunter has also been pictured on the set of the film with Natalie Portman.
The film, which also features Frieda Pinto and Imogen Poots, was previously running under the working title Lawless but will now be released in 2013 under a different name, following the release of John Hillcoat's film Lawless earlier this year.