Plot hole: When Cyborg tells his origin story, he says that the Mother Box in possession of the government was shelved till after the night when Superman died, when it came to life leading it to be studied by Cyborg's father, Silas. However, that contradicts the previous movie, Batman v Superman [both 1 h 39' and 2 h mark], where Batman came upon Luther's metahuman evidence file, including Silas Stone's vlog with the creation of Cyborg that Diana watches. (01:02:35)
Plot hole: If the the parademons can smell the fear and react, they would do so when Flash is having a panic attack.
Suggested correction: The parademons are in a separate room with several hostages who are far more afraid than The Flash is, so their attention is focused elsewhere.
Flash and the others are in the very next room without any door or wall beside the parademons, not too far, and there are 10 or 12 around the space. Anyone can smell Barry's fear or at least hear them, and the hostages show less fear than Barry - he is almost paralyzed.