hero's come back 这句话语法有没有错

没错，‘s是has的缩写，这里是Hero has come back
英雄已经回来了

come back 这是一个动词短语，应该这样说the hero's coming back

有点中文英语的意思.应该是王者归来的意思把.汗的
加上个has好点

那具体要看's指代什么了,要是has的话是可以的

nothing wrong

hero has come back 王者归来

He's got lots of trouble.
He has got lots of trouble.

He's moving on.
He is moving on.