Audio problem: When Richie goes in place of his father to open the tool warehouse, the kids playing baseball gather at the gate and the girl in the middle says something like "Are you crazy? That's Richie Rich, the richest kid in the world." After that line, watch the black kid with a baseball cap to the left of the screen. His mouth moves but there is no voice.
Continuity mistake: When they are in the lab giving Richie a tour instead of a lesson, they are turning trash into bowling balls as an example. Well, the professor rolls all the balls off and into the container at the end of the ramp, then in the next shot he's holding one which he drops on his foot.