In the end jail scene between Felix Gallardo (Diego Luna) and Agent Breslin (Scoot McNairy), on Breslin's close-ups, you can see that a stand-in actor was used for Felix Gallardo. The actor's face is clearly visible and obviously not that of Diego Luna.
When Clavel (Andres Londono) is attacked with a Baseball bat by Héctor Palma Salazar (Gorka Lasaosa), while he is laying on the floor after the initial hit, you can clearly see that the second hit makes no contact with Clavel's head.