The bullet that comes out of the agent's gun is much too large to have been fired from that diameter of gun barrel. Also, the entire shot is poorly timed as the gun recoils too fast relative to the speed of the bullet.
The Flash captures an agent's bullet and turns it around to face him, and when the action resumes, the bullet continues on it's new trajectory into the agent's shoulder. Merely changing the orientation of the bullet is not enough to make it change trajectory, and if he flicked it himself there is no need to point it in the proper direction at that short a range.
Maisie Richardson-Sellers accidentally slips into her natural British accent when discussing how to escape from the "Men in Black" prison in the 1950's.
The character of Thea was dropped from this episode for budget reasons. Oliver mentions dropping her off at home, but no reason is ever given as to why she abandons the team.
The writers were forced to minimize Supergirl's participation due to budget considerations, forcing Oliver to make the illogical decision to sideline her for most of the action.