I doubt that a movie would be considered an episode, and "Light as Day" seemed pretty final. It is more likely that a new Season would be created: starting from either episode 40 or episode 1. However, there is every possibility that it is related to the movies--after all, from what I can gather about the movie from it's summary (and from it's cover), it seems that the plot happens in post-Blakk Slugterra. And if the movie is related to the normal episodes, the regular episodes could also be a countinuation of the movie.

The cover looks awsome!

I know right. Maybe new posters will come out soon

for me i am in canada and up here it said on tv it was ep 40 and 41

Oh yeah I am also in Canada the episode 40 and 41 is Ghoul From Beyond They split it up in two parts in Canada.