Continuity mistake: When Futterman throws the gremlin onto the cement, before moving the slide, the Gremlin's neck and back have no cement, but a frame later they're totally covered in it.
Sacha
Continuity mistake: When Forster is seduced by the Gremlin, his hand alternates between being on her shoulder or on her back.
Sacha Continuity mistake: When Gizmo dances in the lab, the position of the cage door, and the distance between the door and Gizmo changes between shots.
Sacha Continuity mistake: When Futterman is being attacked by the Gremlin, his wife is on the right, a frame later she is standing on the left side, several meters away.
Sacha Continuity mistake: After Clamp kills the Gremlin the desk is clean. A frame later, when Billy shows up, there's a gallon of goo all over the place.
Sacha Revealing mistake: When Clamp has the Gremlin attached to his chest, his left hand is very obviously puppeting the Gremlin's arm. Clamp's fake arm is very long and makes a weird twisted bend around the Gremlin's back.
Sacha Continuity mistake: When water falls on Billy's desk, a small squared object next to the pens keeps changing positions between shots.
Sacha Continuity mistake: The lettuce leaf on Forster's shoulder changes shape between shots.
Sacha Revealing mistake: When the female Gremlin jumps on Forster, his arm is obviously controlling the puppet. His fake arm's awkward position plus a fake chubby hand reveals it.
Sacha Revealing mistake: In the kitchen, Crazy Gremlin throws an ice cream at Kate, which doesn't produce a stain and bounces around, revealing it's a rubber prop.
Sacha Continuity mistake: Amount of green flesh on Clamp's face and suit when killing the Gremlin disappears / reappears.
Sacha Continuity mistake: When the old man is fixing the water fountain, a towel appears / disappears between shots.
Sacha Continuity mistake: After water falls on Billy's desk, the table and floor appear totally dry.
Sacha Continuity mistake: When Billy is tied up in the dentist's chair, he's got a single wire tying him up, but a double wire in the close-ups. The bandage on his forehead is also either covering his eyebrows or not, depending on the angle.
Sacha 
Other mistake: Gizmo can't be exposed to sunlight, yet when the shop is demolished he walks out on the street. Note how he is walking past the shady part of the curb to the sunny part, suffering no harm whatsoever.
Sacha 
Answer: He's at the salad bar when the gremlin pops out and grabs a guy. The guy they grab is former football star, Dick Butkus.
Bishop73