"The Monumental Grouch" is the only time in Season 9 that depicts Bigmouth's doppelgänger who is a cave orge.
"The Monumental Grouch" is the second time in the cartoon series that Painter took the role of Le Schtroumpf sculpteur ("The Sculptor Smurf" in English) who makes sculptors, but does not appear in the cartoon series. The first was in Season Seven's "Stop and Go Smurfs."
While Grandpa and Grouchy appeared in the title card for "Greedy's Masterpizza," they are no where to be seen in this episode.
While Sassette appeared in the title card for "The Monumental Grouch," she is no where to be seen in this episode (which also shares the title card for "Greedy's Masterpizza").