Maura's hair had 6 inches cut off one episode previously, it looks to be the same length as before.
The white iPhone is the secure monitor that was provided with the DEA cameras so that the "hacker" couldn't tamper with the system.
Jane is at the office and is looking at the video from the DEA cameras on her white smart phone. She walks over to her desk with the white phone. She answers a call from Maura on her now black smart phone.
When Jane brings Maura a box of donuts Maura shuts the box almost all the way down after she takes one out, but moments later the box is almost all the way open.
Korsack aims the gun at his chest then swings it around in a cavalier manner so that it is pointing at Maura. No police officer or anyone proficient with guns would ever aim a gun at himself or anyone else. It is a cardinal rule that guns are supposed to be handled as if they are loaded at all times.