I was watching an Instagram video posted by Woody and Kleiny account https://www.instagram.com/p/BqxY4lflIKQ/ and here is a sequence of it:
A: Knock-Knock
B: Who is it?
A: It's the Police
B: What do you want?
A: We just want to talk.
B: How many of you are there?
A: There is two Sir.
B: Talk to each other then.
Question: Why it is right to say there is two, instead of there are two?
Update: I didn't recall it had subtitles. Know I am seeing that was there's.