subject verb agreement - The thing that scares me the most are the little oranges in its stomach

Sally says "The thing that scares me the most are the little oranges in its stomach." at 4:50 in the TV drama "3rd Rock From the Sun S1E3 Dick's First Birthday". https://www.youtube.com/watch?v=Tgj83qt7fqA

Please notice that "thing" is singular whereas "oranges" is plural. I'm wondering which one of the following statements about the sentence is correct.

1. 
   

   It is grammatically correct and perfectly makes sense.

   
   


2. 
   

   It is grammatically incorrect and most people frown upon it.

   
   



3. 
   

   It is grammatically incorrect, but most people think it is natural and don't care.

   
   


4. 
   

   Else.