Filming for Game of Thrones season 6 has begun in Northern Ireland and the first leaked on-set images have surfaced online.

The images do not really reveal much expect that some men dressed in dark colours, someone on a horseback and maybe some extras who could be either soldiers or travellers, reports Game of Thrones fansite Watchers on the Wall.

Earlier rumours suggested that filming for season 6 would take place this weekend on Binevenagh mountain - an area (in Northern Ireland) that was featured in season 5, standing in for the lands around the Vale. "Perhaps the man on horseback is Littlefinger, returning to the Vale?" speculates the website.

Another Twitter user's recent post reveals that the makers are filming scenes involving Daenerys Targaryen in Magilligan. Apparently, actress Emilia Clarke was spotted at the location. Incidentally, this is the same location where the final season 5 scenes featuring Daenerys were shot.

Meanwhile, all clues point towards Jon Snow's return in season 6. Apart from the fact that actor Kit Harington was spotted with the rest of the cast in Belfast recently, a filming location for season 6 has fuelled rumours that the show is not done with Jon Snow yet.

An iO9 report states that the show is headed to Guadalajara, Spain to film at the Castillo de Zafra. The structure bears an uncanny similarity to a description of the Tower of Joy - which is prominently featured in flashbacks to King Robert's Rebellion - as the place where Ned Stark's sister Lyanna was found dead.

If the Castillo de Zafra is the Tower of Joy in the show, it could confirm one of the most popular Game of Thrones theory on Jon Snow's true parentage:

A popular Game of Thrones theory about Jon Snow (R+L=J) suggests that he is actually the son of Ned's sister, Lyanna Stark and her captor, Rhaegar Targaryen.

According to the theory, Lyanna was kidnapped by the Targaryen prince, which sparked Robert Baratheon (Mark Addy) and Ned's successful rebellion. However, before they could take King's Landing and dethrone the Mad King, Ned found his sister dying in a bed of blood. With her last breath, she made him promise her something unknown.

From there, fans started speculating that the promise was to pretend that Jon was his illegitimate child so that he wouldn't be murdered by Robert – who was going on a killing spree to wipe out each and every Targaryen. As per the theory, Jon Snow will hold a claim to the Iron Throne by birthright.

Also, if that is the case, then maybe Jon Snow will feature only in flashback scenes in season 6...prior to the time he left to join the Night's Watch. Now all we need is for someone to spot Sean Bean on GoT season 6 sets and this theory is confirmed!