When Angela's neighbor goes to the food truck to meet her; there is a short line with two women in front of him and one man wearing a backpack in front of the women. However, in the next cut after Angela had an anxiety attack and looks out the window the man is the only one in line and the two women that were seen before are approaching the line from the opposite end of the food truck.
The nail gun Angela used to ward off her attackers was a pneumatic nail gun. It wouldn't have worked unless she had it connected to an air compressor. This is an unwitting reference to the same type of goof when Murtaugh uses a disconnected nail gun to kill a home invader in Lethal Weapon 2 (1989).
A pneumatic nail gun cannot do much damage unless it were to puncture the heart or an artery - and then, not so bad unless it were pulled out. A nail of the size shown shot into the skull would not be innately fatal. It would not do very much damage to speak of.
Angela receives text messages despite her phone being turned off. However it is clearly seen that Yuri remotely activates her device from his computer. This is why Angela throws her phone away as she realizes it is compromised.
Angela's keys go from 1 single key to several ("janitor's") keys on a different key-ring. However, the single key with the puzzle piece key chain is specifically for the middle deadbolt which may have not been locked when Angela leaves. Therefore, she would have only needed the "janitor's keys" and not the single key to get back into her apartment.
On one recording, the knocking on the door is heard but the character did not yet "wake" Kimi up and asked it to start recording.
At 21:50, Kevin the neighbor watches Angela with his binoculars but she is the same size as when looking from one building from another without binoculars (the camera should have captured the images with a zoom).
When Angela texts her neighbor to meet her in 12 minutes at the food truck; there is a male customer wearing a plaid jacket and backpack waiting to order. However, when her neighbor is at the truck; the male customer is still there waiting to be served. Additionally when she looks out her window again even after her anxiety attack; that same male customer is still there and about to be served. There wasn't much of a line so normally it wouldn't take 12 minutes plus for the customer to be served especially since no one was in front of him and was next up to be served.
When Yuri is supposed to be entering her phone number using the numeric keypad the keys he hits don't match her phone number. Then, when entering text he randomly types in the same small central area of the keyboard really fast using all his fingers.
Even though her character is portrayed as this person with good audio software/hardware knowledge and obsessive attention to detail, she wears her Audio-Technica headphones the other way around in the entire movie.
Angela and Ms. Chowdhury talk about a retinal scanner at the entrance of the office building, and how they obtained Angela's retina image using the video conference tool. The scanner actually checked the iris, not the retina (also, the iris image can be sampled during a video conference; retina images cannot be captured without specialized equipment).