(at around 38 mins) When the professor writes "Djinn" on the blackboard, the line he draws underneath is nowhere near the cursive writing on the board. After the walks around the room and goes back to the board, the word "Djinn" is different with the line underneath cutting into the cursive writing.
(at around 21 mins) After both She Demons disrobe their bras and skirts, their clothing is seen on the floor, however, after both She Demons engage in sex with Joel, their clothing are nowhere to be found.
When Diana goes back to the museum to see if the professor's okay, she goes down a grand staircase. Earlier, she went UP that same staircase to go to the same room.
(at around 1h 20 mins) While the Djinn is on the roof of the car, buildings in the background come and go and change throughout the scene.
(at around 1h 21 mins) The car's damaged right front headlight area appears to have fixed itself right before the car makes the leap and crash.
(at around 24 mins) When the professor's face is taken off by the Djinn, instead of seeing muscles underneath, you see his real face covered in fake blood. It's especially noticeable around his eyes where there's hardly any fake blood, so you see his eyelids and eyelashes. You can even see his right eye move underneath the eyelid.
The Djinn is aggressive in his methods of provoking wishes from his victims yet he doesn't do so when he confronts Professor Joel Barash, in fact, he's acting like how the Djinn is supposed to by offering Joel the chance to make his wildest dreams a reality only to twist it into a nightmare after the wish has been granted. But it's inconsistent with his attitude towards the others like when he threatens Greg that he will kill him and Diana's closest friends horribly if she doesn't make three wishes.
It's been established in the previous two films that a Djinn can only act when wished to do so; yet in this film, the Djinn is grabbing people, throwing them around, and even threatening to straight up kill them, without a wish of any kind being made to grant him the liberty to harm them.