Throughout the film there is an intentional and specific use of the American flag, which the director felt was important to capturing the way issues of race and white supremacy are intertwined with the fabric of America.
During the living room scene when Ames dominates Blaze, there's a safety pin on her nurse scrubs (also visible when she returns to the couch). At the time of production, and in the wake of Donald Trump's presidential victory, the safety pin emerged as a symbol of unity: a way for people to show they would not stand for the kind of violence that had emerged since Trump took office. Ames takes advantage of this symbol in order to mislead those who don't know what she really stands for; a comment on how easily well meaning actions can be co-opted.
That moment when Bryce drips saliva into Blaze's mouth was unscripted. Originally, his character was supposed use the DNA sample from earlier in the film, but during production the prop was left at a previous location. In the moment, with no prop on hand, Director Christopher Greenslate asked both actors in the scene if they would be comfortable with the spit, and they agreed while performing that they could adjust. It was this kind of real-time communication that made the film possible.