When Beldar is reading out his fake security number, his bottom teeth are clearly human teeth. However, when Otto complains to Beldar that he needs to get his teeth fixed, Beldar has sharp teeth on the bottom.
After successfully knarfling the Garthok, Beldar is suddenly covered with drops of blue blood. This is because a scene of him cutting of the Garthok's head was deleted. The head is still seen lying next to him on the steps in some shots (with the blue, bloodied stump facing the camera)
After the Coneheads return from Remulak, we see Beldar's golf trophy in his living room. Just to the left of the trophy, we see the makeshift golf club Beldar had when he "knarftled the garthok" on Remulak. However, when they exited the spaceship after they returned to Earth, nobody was carrying it.
In the scene at the swim meet, you can clearly see that Connie does not have the Gorelks at the small of her back, which all Coneheads have. These are two handle-like growths, which can be seen on Beldar in his shower scene at the golf club.