Prior to season three, MacLaren's communication device was on his left side. In Ilsa (2018), his communication device switched to his right side. This time, it changes back to his left side.
Marcy tells David that she is saving him from salmonella by stopping him from eating raw eggs. She then proceeds to crack eggs into the bowl and leaves pieces of shell in the eggs. Salmonella in almost all cases is transmitted via the shell of the egg, not the contents. As a doctor Marcy should understand the concepts of cross-contamination and the function of how salmonella is spread. She should have immediately removed the eggshell.
When Carly opens the apartment door for Jeff, the door opens outward. Generally, residence doors open inward (because having the hinges on the outside would be make the door much less secure). But having the door open outward made it much easier to get a dramatic shot of her aiming the handgun at him.