According to Gizmodo.com, "The MCU’s special effects get more and more impressive, from de-aging that looks actually realistic to Josh Brolin’s impressive performance as a half-human half-CGI Thanos." Kelly Port from Digital Domain explained the makeup, “From a technical perspective, we used a technical innovation from machine learning, on this project, that hadn’t been done before. That allowed us to get that subtlety, which was really important. With those subtle performances, it wouldn’t have been as effective or as believable, as a character. It certainly wouldn’t have been able to convey a non-dialogue performance as well because it was so subtle."