PeelSeel2
Explorer
I was in the middle of making the following post, when I started thinking about it and looking for examples, when I realized in this edition it is wrong.
It is better to say they automatically damage. Since there is no attack roll, they don't trigger things that say "on a hit".
In 5e Magic Missiles do automatically "hit", this doesn't do much as there is very little other effects that could trigger on a spell hit that is not built into the spell.
Two of the interesting ones I found were the rogue assassin subclass ability "assassinate" that turns any hit on a surprised creature into a critical hit and attacking an unconscious creature while within five feet of it that also turns any hit into a critical hit. So normally a magic missile spell can not critically hit because there is no attack roll, these two exceptions allow the spell to.
You can only crit when you get an attack roll. Magic missile and assassinate will not combine.