RKC Waalwijk
In August 2011, after his first season with the first team of Ajax, it was decided that Castillion would go out on loan to RKC Waalwijk for the duration of the 2011–12 season. He made his debut for RKC Waalwijk on 7 August 2011, and two weeks later scored his first Eredivisie goal while playing for RKC Waalwijk. In total Castillion made 29 league appearances for the club from North Brabant, while scoring a total of six goals during league play.