We study the Choquard equation involving mixed local and nonlocal operators \( -\Delta u + (-\Delta )^{s}u + V(x)u = \left( \frac{1}{|x|^{\mu }} * F(u)\right) f(u) \quad \text {in } \mathbb {R}^{2}, \) where \(s\in (0,1)\) , \(\mu \in (0,2)\) , \(F(t)=\int _{0}^{t} f(\tau )\,d\tau \) , and f has subcritical exponential growth of Trudinger–Moser type. Under suitable assumptions on the potential V and the nonlinearity f, we prove the existence of a least energy positive solution by a Nehari manifold approach. We also establish the existence of a sign-changing solution by means of invariant sets of descending flow. If, in addition, the nonlinearity is odd, then the problem admits infinitely many sign-changing solutions.