It's a complex sentence with an attributive (relative) clause. The main clause: There's a couple of things. Subordinate clause: that you need to pay extra attention to.
There - formal introductory subject.
Only a couple of things - notional subject group
Is - existential predicate
That you need to pay extra attention to - attributive (or relative) clause
That - relative pronoun, its antecedent is 'a couple of things', indirect object
need to pay - modal predicate
extra attention - direct object
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