When Bass and his partner show off the pipe line to Nitti nothing comes out of the pipe. Turns out Ness had disconnected the pipe below the floor. The pipe had held beer when tested earlier so there would have been beer left in the pipe after testing and it would not have been empty.
In the prison library scene, Jason Fiddler is holding a ballpoint pen, and their invention was still years off.
Frank Nitti mentions how Eliot Ness had bedeviled Al Capone for four years. Capone was sent to prison only two years after the Untouchables were formed.