Launch point of Grenades not aligned with throwing animation
From Worms Knowledge Base
Though the animation for throwing Grenades, Cluster Bombs and Banana Bombs in the PC, PSone and Saturn versions of Worms shows the Grenade being bopped from the forehead, the actual launching position of the projectile once it begins traveling is above the top of the worm's horizontal position, rather than the position as seen in the animation.
This bug is not present in the Amiga, Super Nintendo or Sega Mega Drive/Genesis versions of the game.