In the final scene of this episode we see Dwight Dixon opening Chuck's empty coffin. In this scene we see the hinge of the coffin on the right side (from an outsider's perspective), however when Ned open's Chuck's coffin in the first episode, the hinge is on the left.
Ned's mother dies when he was about 9. In this episode he says that when he was 9 he saw his half brothers who looked to be about 4-5. Unless his father had a second family before his wife's death there is no way that that could be.
Chuck carries a supposedly functional metal detector past a suit of armor, but the metal detector does not beep.
When Ned brings the Great Hermann back for his 1 minute chat, you can see the "cement" jiggle, wiggle, and move every time Hermann talks or moves his hands. Although no one watching would believe he was actually in real cement, it's pretty clear it's just foam.
The Narrator says, "The facts were these: on a cool autumn day nine years, 48 weeks, 26 days, and seven hours earlier ...." 26 days is three weeks and five days, so this is the same as nine years, 51 weeks, and five days.