Grifting 101 - S6-E9
Continuity mistake: The stacks of money the dean takes out, before getting up, changes in the next shot. One stack is completely on the black edge, then is only partly against it and closer to the other stacks. And the stack on the other end is bigger.
Advanced Safety Features - S6-E7
Continuity mistake: When Rick and Britta are talking to Todd, they're holding hands. In one shot, Rick has his hands clasped together and in the next shot, back to holding Britta's hands.
Grifting 101 - S6-E9
Continuity mistake: When the grifting professor and Jeff are speaking in their office after meeting each other, we see the bottle of alcohol change amounts as the camera moves angles (from Jeff's POV to the teacher's). It is lower when the teacher is all alone, and there's more when it's Jeff's POV. (00:20:14 - 00:20:36)
Continuity mistake: Britta has a cellphone in her right hand. The camera cuts to behind her and she's flailing her right hand with no phone in it. In the next shot, the phone has jumped to her left hand. (00:13:05)
Laws of Robotics & Party Rights - S6-E5
Continuity mistake: Jeff writes the word "Law" on the board and draws out his "born into dirt" story. A few cuts later, after Garrett asks him when he stopped being funny, the word "Law" looks much different, and the other parts look redrawn. (00:13:30)
Laws of Robotics & Party Rights - S6-E5
Continuity mistake: Jeff is facing Willy as Willy asks him where he was born. Still facing him, he responds, but before he finishes his sentence, the camera cuts and he is how facing completely away from Willy and is drawing on the chalkboard. (00:13:20)
Lawnmower Maintenance & Postnatal Care - S6-E2
Continuity mistake: Elroy is holding the Dean in virtual reality. In real life, his hand is in front of his face and slightly opened. When the camera cuts closer, his hand is lower and clenched in a tight fist. (00:21:00)
Lawnmower Maintenance & Postnatal Care - S6-E2
Continuity mistake: Britta is running out of her parents' house, leaving the door behind her closing. In the next shot, the door has stopped moving and is opened up more. (00:16:55)
Continuity mistake: Britta sets down a tray with a sandwich on it horizontally right in front of her. In the next shot, it has now moved further away from her and is sitting vertically. (00:12:05)
Grifting 101 - S6-E9
Continuity mistake: During Professor DeSalvo and Jeff's argument, the amount of scotch in DeSalvo's glass changes a few times between shots. (00:08:40)
Basic Crisis Room Decorum - S6-E3
Continuity mistake: Chang is holding a piece of paper by the top, showing it to everybody. In the next shot, he is holding it by the side. (00:04:15)
Queer Studies & Advanced Waxing - S6-E4
Continuity mistake: At one point earlier in the episode, Elroy mentions that there are two baby birds in the nest that needs to be moved. Later, after the nest is moved, Abed mentions that there are three baby birds - two died and one survived.
Answer: His attempt to "kill" Jeff was to roll at him as an iPad on a stick. He knew it wouldn't work, but it played to the story that he was a killer as he knew Jeff would tell people about it, or attempt to retaliate for it.