What specific scenes or symbols are used as an example of loyalty or disloyalty in On the Waterfront?

I would say that when Terry talks to his brother about
what could have been the result of his life, it is a moment where one sees the tension
between loyalty and disloyalty.  It is one of the most famous scenes in the film because
it is so emotionally uncomfortable to see the pangs of loyalty hit against the dissonant
chords of disloyalty.  When both brothers are talking, Charley trying to get his brother
to take the bribe in order to be silent, and Terry speaking about how his brother should
have "looked out" for him, it is a stunning moment about loyalty and disloyalty in a mob
controlled world.  Terry reminds the viewer about what loyalty should be and how it
stands in stark opposition to what the world of disloyalty looks like.  It is a scene
where the collision between both realities is present, as Charley embodies disloyalty in
how he manipulated his brother, and Terry is tortured in trying to represent loyalty in
a world that does not validate it.  I think that it is here where we see the greatest
symbolic representation of loyalty and disloyalty, simultaneously, in the
film.