Continuity mistake: In the scene where Inga, Fredrick and Igor throw the net over the monster, Inga sticks the syringe of the sedative in the monster's back but does not push down on the top, yet the monster still falls over. A few seconds later when she collapses on the monster, you can see all of the fluid inside spray out.
Trivia: Another time you can see Gene Wilder laughing when he's not supposed to be is after he finds out the project failed (the quiet, dignity, and grace speech). He starts strangling the monster, and you can see that he is stifling laughter. Finally, he can't hold it in any longer and proceeds to partially hide his face behind the monster lying on the table in an attempt to cover up his smirks (but you can still see that he is laughing).
Add timeMovie_Freak 1
[A wolf is heard howling in the distance.]
Igor: [Points to moors] There wolf. [Points forward] There castle.
Frederick: Why are you talking like that?
Igor: I though you wanted to.
Frederick: No, I don't want to.
Igor: Suit yourself. I'm easy.