Character mistake: When Dracula puts Johnny on a time-out, it is shown that Dracula has the ability of psychokinesis. Yet during the scene when Mavis visits the human village, when one of the dressed up zombies loses its head, Dracula jumps into the scene to physically put the head back to its body, further risking being spotted by Mavis, which he wanted to avoid. (00:16:15)
Suggested correction: Using this power would also be a risk of Mavis finding out because his magic has blue effects around which she would spot.
I doubt that, she was facing the opposite direction of the headless zombie the entire time, and the zombie didn't stand too close to her. However, I have realised that the magic does seem to make sound, and the headless zombie did stand close enough to Mavis for her to would have heard Dracula's magic if he were to have used it.
Even with the sound, I doubt she would have noticed when there are what looks like villagers approaching her with pitchforks and torches.
Question: During the party near the ending, why did the guests panic when they saw Jonathan's true identity?
Answer: Throughout the movie, Dracula has been drilling into his guests the history of humans' mistreatment of monsters, hence the building of the hotel, which was to be a monster's refuge from the human world. Most of the monsters likely had never interacted with humans, so that coupled with the stories from the past caused the monsters to freak when they saw Jonathan's true identity as a human.
But they had been hanging out in the hotel for long and johnny wasn't a bad person so the shock is unjustified.
The fact that he'd been hiding his identity the whole time would be enough for anyone to be concerned, especially when the reality was that he was a human, who they all have been in fear of for centuries.
Answer: Part of the shock would be him lying all this time, or the possibility of him being a fake Johnny.