看看这句有语法错误吗~~~~~`

这句话错误，正确的应该是：
I visited my friends, and we played basketball.
I visited my friends. We play basketball.

不是，应该用-ed形式，前后一致~

应该是过去式，played，因为前面的visited也是过去式。
而且，这个句子有点别扭，应该说when i visited my friends, we played basketball

楼上正解！