I'm not sure if these are very significant, but I noticed some parallels between this parable and the account of Cain and Abel in Genesis 4. The most obvious is that each story is about two brothers who have contrasting qualities. Also in both, the elder brother becomes angry with the younger brother, who - in the older brother's view, at least - receives preferential treatment (Abel's sacrifices are accepted by God, but Cain's aren't; the prodigal son is honored by a party upon his return, but his older brother never received even a young goat), and each younger brother deals with livestock of a sort: Abel kept sheep, and the prodigal son fed pigs.
