Differential games are an important mathematical tool for studying conflict in applications across engineering, economics, and ecology. In noncooperative differential games, the players (or decision makers) are concerned with achieving their individual objectives under the dynamic constraints of a system governed by differential equations without relying on the cooperation of others. In this paper, we propose three methods of inverse noncooperative differential games that enable the recovery of player cost-functional parameters from open-loop Nash equilibria. We first propose a nested optimisation approach that provides a direct method for solving inverse differential game problems. We then develop connections between our inverse noncooperative differential game problem and the existing problem of inverse optimal control to propose two alternative methods with modest implementation and computational demands. We illustrate and compare our three methods in simulation.