In the movie Saving Private Ryan beach invasion what exactly were the explosions that dropped and threw sand in the air around the beach?

88's and mortar fire.

They were special effects that did not endanger the actors.

Goosh

The Germans could not believe the landing was actually taking place so reacted poorly. They had about zip air support so what you see is local artillery and mortor rounds. There were also buried land mines.

They did drop from the Sky. Ever Heard of Motors or Cannons??

or what they did was bury airlines in drums or pits and when the actors ran around they would push the air thru lines blowing sand and stuff into the air.making it look like it was a motor round or bullets....on movie sets the explosions you see in the movies with the fireballsandsuch arepretty much CDI . the actual explosions are tiny....

artillery mainly, some were some of the few bombs dropped by axis aircraft