Each of the choreographed fight sequences involving Thana Terc and Thana Sec were shot on two different days and months apart.
The first scene on the Chin Hua alien colony wasn't in the early drafts of the script. It was added a couple of months before production was expected to end.
In the final scene, Lieutenant Willets says he met India at a screening of the movie Love Eterne. Love Eterne is an actual film directed by Joseph Villapaz.
Due to director Joseph Villapaz's love of Shakespeare's works, the scenes with The Premiere, The Regent and The Obsidian were intentionally created with a Shakespearean influence. In addition, Thana Terc's final line "How does that Shakespeare quote go" is indicative of this.
In each of the three choreographed fight sequences where Petra confronts the Thanas, Petra's wardrobe changes from gray (with Thana Terc), blue (with Thana Sec) and purple (with Thana Prime) to black but no apparent to any of the characters. This was a stylistic choice indicating darkness when fighting. This is also apparent during the scenes with The Premiere, The Regent and The Obsidian when their wardrobe gradually turn all black when things get more desperate.