The effects of cluster correlations have been studied in the C12+C12 reaction at 50 MeV/nucleon, using three antisymmetrized molecular dynamics (AMD) models, the AMD (AMD/D) without any additional cluster correlations, AMD/D-COALS with nucleon correlations based on a coalescence prescription for light cluster formations with A=4, and AMD-cluster with an extended cluster correlation in two-nucleon collision processes and a special treatment for intermediate fragment formation with A=9. The angular distributions and energy spectra of fragments have been simulated and compared with the available experimental data. It is found that the cluster correlations take a crucial role to describe the productions of light charged particles (LCPs) and intermediate mass fragments (IMFs), and the AMD-cluster studied here provides a consistent overall reproduction of the experimental data. It is also shown that the significant effects of the secondary decay processes are involved for the fragment production besides the dynamical productions in the AMD stage. Detailed LCP and IMF production mechanisms involved in the intermediate energy heavy ion collisions are discussed.