In formal English, the correct sentence is:

The verb (to be) has to agree with the noun that follows it (things).

Nevertheless, your observation is accurate: lots of native speakers use the expression "there's" even if the noun that follows is plural. This is very common in informal conversation. One could say that the term "there's" is becoming a separate piece of vocabulary, meaning something like "the situation is the following". For example:

The situation is the following: three people at the door.

The situation is the following: lots of cars in the parking lot.

Language is changing all the time, so what you hear out there is not always what grammarians recommend. To be more precise, grammar is only an attempt to explain language, which is a natural and dynamic phenomenon.