In one shot Dr. Stanz is on the roof of the Ecto-1 ready to use the proton gun. In the next shot, he is not on the roof; the following shot places him on the roof again.
After Egons wheels out Peter's Ghost Attractor and starts to explain his modifications, Egon is drawn in a much larger size than the other Ghostbusters, even though he is further away from the camera. Making the other Ghostbusters look like little children standing in front of him.
The very premise of the episode does not make sense. Peter invents a Ghost Attractor and believes that the invention will make the Ghostbusters "millions of dollars." The Ghostbusters then are seen trapping hundreds of ghosts at the firehouse and Winston says "business is too good." In reality the Ghostbusters would not have seen any money for trapping the additional ghosts; they make their money by charging clients whose homes or businesses are haunted with ghosts to remove their ghosts. By attracting all the ghosts to the firehouse they would not only be working for free, they would essentially be putting themselves out of business by removing ghosts from the homes and businesses of potential clients. Even though the Ghost Attractor never actually worked, the decision to build it would not have made them money.