Hole
We see a hole in Jaibo's pocket after he orders a sandwich from a vendor. It is a symbol that he has no money, and even if he did he is prone to losing it.
Bull Fighting
We see boys from the street gang Jaibo leads pretending to be bullfighters and bulls. The symbol is that there will be fighting amongst these boys to come.
Milk
We see Eyes sucking on the nipple of a donkey to get milk. This is a symbol that these boys have been malnourished by their parents and have had to resort to feeding in unnatural ways.
Sling
Jaibo wears a sling when he goes to accuse Julian of ratting on him. It is a symbol that he is willing to do anything in order to get what he wants, including deceiving people making them believe he is helpless when he is really dangerous.
Corpse Tooth
Eyes gives a tooth from a corpse that he wears to Meche. It is a symbol of his affection for the young girl.