As John Brown wakes up after being transformed into Inspector Gadget, he falls off the right side of the table. An overhead shot of the operating room shows him on the other side of the table as he is getting back up.
In the scene when Scolex brings RoboGadget to life, in the close up shots of RoboGadget's head, the collar of a grey t-shirt can be seen. But in shots where we see his body, it is all machinery below his neck.
When Robo-Gadget is going through the city pretending to be Godzilla by making the shape via his hands, from the shadow on the wall it is obvious that whatever is making it is on rods and not his hands.
When inspector gadget is fighting robot gadget on top of the bridge, for a second or two you can clearly see Matthew Broderick's stunt double's face. This happens right before Matthew calls for "time" out.