In the beginning of the episode (roughly 30 seconds in), during Selina and Gary's brief exchange about a dog, every time the camera angle changes, the iPad is flipped. Seeing as the camera angle's changes are split-second events, this part of the scene was clearly filmed multiple times.
When Selina fist-bumps Dan, Mike can be seen walking away from the group behind them. In the next shot, though, Mike is still there and hasn't moved.
When Mike is asked about his (fake) dog, there is an off camera comment "Simon? what an unbelievable name". The voice does not match any of the characters in the scene.