io9 found the snippet of video from the DVD set in which show creators David Benioff and D.B. Weiss acknowledge in the commentary that the 43rd president's head is one of those up on pikes surveilled by Sansa Stark (Sophie Turner): "The last head on the left is George Bush. George Bush's head appears in a couple of beheading scenes. It's not a choice, it's not a political statement. We just had to use whatever head we had around."
Naturally, this has made some Republicans irate, and lead HBO to issue an apology in which they said the head wasn't there for political reasons but practical ones. From Deadline:
David Benioff and D.B. Weiss: We use a lot of prosthetic body parts on the show: heads, arms, etc. We can’t afford to have these all made from scratch, especially in scenes where we need a lot of them, so we rent them in bulk. After the scene was already shot, someone pointed out that one of the heads looked like George W. Bush. In the DVD commentary, we mentioned this, though we should not have. We meant no disrespect to the former President and apologize if anything we said or did suggested otherwise.
The bigger question for me is how a business can sustain itself on bulk head rentals -- is it that steady an industry?