Production code is 112.
Mandark has mind-reading powers in his first appearance, "Dexter's Rival", but no longer has them in his next appearance, "Mandarker". No explanation is given.
Dexter and Mandark are asked, "What is the name of Neptune's moon?" and Mandark answers "Titon". Neptune has been known to have a second moon, named Nereid, since 1949. In 1989 six more moons were discovered therefore they were known when this episode was aired. Between 2002 and 2003, five more moons were discovered. Triton, though, is the largest of all of them.