So we get introduced to Grover Cleveland's Presidential Time Machine in the Season 1 episode "Are You There God? It's Me, Dean." But we don't see it being used. If I'm not mistaken the next time we see it is in the Season 7 episode "The Forecast", where it's not only mentioned, but a time traveling Billy, and Rusty (presumably from some adventures including a visit to Civil War America, and the Titanic?) come out of it. Now, let's presume the time machine mentioned in "Escape to the House of Mummies Part 2" is Grover Cleveland's (cause let's be honest it probably is), do you think the Billy and Rusty that came out of the time machine during "The Forcast" are from "Escape to the House of Mummies Part 3?