
Continuity mistake: When James and Kat first enter Whipstaff Manor, they drop their stuff on the floor. The large suitcase falls over on its side, but it cuts to the overhead wide shot and the suitcase is standing upright (the ghosts didn't do it). (00:19:45)
Answer: When Carrigan tosses the Whipstaff documents into the fireplace, one paper's hidden message appears on the back from the heat (if using lemon juice instead of ink, messages stay hidden and only appear when heated); it has a drawn map and handwritten "Buccaneers and buried gold, Whipstaff doth a treasure hold." Later, Casper tells Kat that he and his dad had great fun together playing pirates down in the lab, and Casper quotes the words from their hidden "pirate" message. So the handwritten note with map was actually part of their father/son beloved pirate-playing shared fun (note when the living Casper appears at Kat's party, he wears a piratey costume with a sword at his side). The pirate "treasure chest" contents were merely Casper's personal treasure: his glove and cherished autographed baseball, and it was kept in the lab's vault; even after Casper succumbed to pneumonia, Mr. McFadden kept it in the vault.
Super Grover ★