There are a few things that movies get wrong about grenades:
Lobbing (throwing the grenade in an arc).
In real life, nobody lobs a grenade. If you throw your grenade in an arc, your enemy might catch the grenade and throw it back to you. Instead, you throw the grenade in a straight line at your target, with as much force as possible. This way, the grenade will spin and bounce around after landing and the chances that someone catches it are much lower.
Removing the pin.
Before you pull the pin from a grenade, you should straighten its two ends.
A Soviet/Russian F1 fragmentation grenade
Like in this picture, most grenades have a split- pin which has its two ends bent, mostly for safety reasons. However, it’s quite difficult to pull the ring out of the grenade without straightening the pin first, as it requires a lot of force. I’ve never seen a movie that got this small detail right.
There isn’t really that much to see when a grenade explodes. A short flash of light, some smoke and dust, that’s it. At night, the flash might look a little bit more impressive, but it’s still far away from the fireballs in the movies.
Although visually a grenade might not live up to a movie-goer’s expectation, they make quite a lot of noise, though. Together with a friend, I once threw a hand grenade at night in front of our base in Kosovo. When our commander came running out of his office and demanded what had happened, we told him that it was a bomb from a NATO plane that had exploded somewhere (we had to lie, because we weren’t supposed to throw around hand grenades at night for fun). He believed us: Hand grenades make a big noise.
The difference between a Socialist and a Communist is that the Socialist doesn't have all the guns yet