Continuity mistake: When Billy shows Marla his new sketches she is holding a notepad and a briefcase. Her hand on the notepad change position between the shots. (00:10:00)
Continuity mistake: As Billy grabs Gizmo out of the cage he grabs him with both hands. When it cuts he only holds him with one hand. (00:19:55)
Continuity mistake: When Clamp introduces himself to Billy, Billy is holding a pen. The way Billy holds the pen changes several times between the shots. (00:22:55)
Continuity mistake: When the drawer opens and Clams asks what's up with the drawer, Billy says it opens automatically while having his hands in his pocket. When it cuts his arms are crossed. (00:23:15)
Continuity mistake: When Forster grab the painting from Billy, the way he holds it differ between shots. (00:25:25)
Continuity mistake: When the waiter presents the chocolate moose, he holds and empty hand in front of the moose. When it cuts a plate suddenly appear in his hand. (00:32:40)
Continuity mistake: When the Futtermans arrive at Billy's and Kate's, we see Murray standing in the doorway with the luggage. On his right luggage there is a paper bag lying on top of it. When it cuts the paper bag has moved over to the other side. (00:35:30)
Continuity mistake: When the gremlins are throwing pans in to the microwave, the display on the microwave is reading 9:20. As the gremlin gets hit by one of the pans the display is off. When it cuts the display is back on reading 9:20. (00:41:25)
Continuity mistake: When Gizmo falls down the hatch he lands on the cocoons. As he land on the floor you can see some green slime on his chest. A few shots later the slime is all gone. (00:41:30)
Continuity mistake: When the gremlin drinks the brain hormone, it starts shaking knocking over the bottle. When it cuts the bottle is back up. (00:57:35)
Continuity mistake: As the crazy Mogwi changes from a ball to an actual creature, a can suddenly changes position on the shelf above, though nothing touches it.
Continuity mistake: When Futterman walks backwards to avoid the flying Gremlin, the passers by are not consistent between shots.
Continuity mistake: Right before Mr. Futterman is attacked by the flying gremlin his coat is already scratched up from the claws.
Continuity mistake: When Billy and Kate return to the Clamp building as the Gremlins hatch, look closely - Kate is wearing beige/tan colored pantyhose/tights in the first scene of them running to the building. ("How long do they take to hatch?", "Not long enough, come on!") Almost immediately after arriving, Kate is told to begin her duties as a tour-guide, and thus doesn't have time to change her outfit. However, in one of her next scenes, she is suddenly wearing brighter cream-colored pantyhose/tights. (And given her fairly consistent screen time as a tour-guide, it's clear she didn't have time to change this one part of her outfit).
Continuity mistake: The pots inside the microwave during chaos in the kitchen change positions between shots.
Continuity mistake: When the crazy Gremlin pops out of the pot, his right arm swaps between being covered in noodles or not, back and forth between shots.
Continuity mistake: When Marla is trapped in the web, she either has a huge web in front of her, or nothing at all, depending on which angle is focusing.
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.
Continuity mistake: When attacked by the flying gremlin, the running blood on Futterman's forehead and face decreases between one frame and another.
Continuity mistake: Billy uncovers Gizmo's cage but a frame later the cloth is back on.
Answer: She only saw him briefly, never in full light either. Plus, it was some time ago. I don't think she would suspect there is another one either.
lionhead
At the end of the first movie, after killing the gremlins, everyone is at Billy's house, and Kate puts a thermometer in Gizmo's mouth and looks directly at him while doing it, giving her plenty of time to look at him.
Still, very briefly, still in low light. She has had way less interaction with Gizmo overall.
lionhead