Jack describes the sword blades in the Cabinet of Doom as "spikes", even though they're not.
Monte makes a great deal of pointing out that only the top five auditioners will perform in the contest, and Montarro is one of the finalists. But the killer has to kill someone for Montarro to perform his illusion. It is never shown that Montarro auditioned, or that anyone died so he could successfully audition.
There's no pendulum in Jack's "Pendulum of Death" illusion.
The noose around Robert's neck is not tight enough to have killed him: it is merely resting around his neck when it would be dug in because of supporting the hanging weight of a full-grown man.
Jack says that his stage name is "The Mad Marshak". Later, during the audition, Micki calls him "The Magnificent Marshak".