The phrase "then and there" is often used to indicate a particular moment in time, implying a sense of immediacy. However, there are several synonyms that can be used in its place, each with a slightly different connotation. For instance, "instantly" implies that an action was taken immediately, while "immediately" suggests that something happened without delay. "At that moment" emphasizes the specific timing of an event, while "on the spot" highlights the suddenness of a decision or action. Ultimately, the choice of synonym will depend on the context and desired emphasis, but each option can effectively convey a sense of urgency and immediacy.