Dental Consonants
In most languages of Europe and Asia, T, D, N, L and R are "dental", i.e., produced by placing the tip of the tongue behind the upper teeth. This is not the case in English, where the sounds arise when the tip of the tongue touches the upper gum ridge. The difference may seem minor, but non-dental T, D, N, L and R are tell-tale signs of an Anglophone accent.
The R is trilled against the upper teeth.