This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Indiana Jones and the Temple of Doom
Indy (under Mind Control) slapping Short Round. The boy's reaction is what really sells it. He pulls on Indy's arm, seemingly thinking everything will be okay, only to get struck to the floor. "Doctor Jones...!"
Similarly, Willie trying desperately to snap him out of it. The sheer terror she must have been feeling at this point is unimaginable.
All those innocent children being forced to work in the mines is heartbreaking to watch.
Also the haunted looks of their mothers and grandmothers in the village, who don't even know if their children are still alive.
What happened to the poor shmuck who was sacrificed by the cult just before the good guys got caught.