LGSWE: [at page 186]
In conversation, however, we frequently find a singular form of be followed by plural noun phrases. The verb is regularly contracted and attached to the preceding there.
Gary, there's apples if you want one. (CONV)
In fact, such examples are somewhat more common in conversation than the standard construction with plural verb plus plural noun phrase.
The special behavior of there's is matched by a similar tendency for here's, where's, and how's.
Here's your shoes. (CONV)
Where's your tapes? (CONV)
How's mum and dad? (CONV)