Today was the Smith family’s reunion. Is this sentence correct? Are there any spelling or punctuation errors?

It's correct, yes.

No errors. :-)

It should actually be: Today is the Smith family’s reunion

Random needs to explain that.

???

Well I thinking it would occur today, but i don't know what context the user wants

If your statement was made before the reunion started, you'd be right. But if it was made in the afternoon after the reunion was over, it would be wrong.

To determine whether this sentence is correct and if there are any spelling or punctuation errors, we can follow a few steps:

1. Read the sentence carefully: "Today was the Smith family’s reunion."
2. Check for capitalization: The first word "Today" is capitalized correctly since it starts the sentence.
3. Look for spelling errors: As for spelling, the sentence appears to be correct. However, it's worth noting that "Smith" should be capitalized since it is a proper noun.
4. Check for punctuation errors: The sentence includes an apostrophe in "family's" to indicate possession, which is used correctly. Additionally, the sentence ends with a period, indicating the completion of a statement.

Considering these steps, the sentence "Today was the Smith family’s reunion" appears to be correct. The only suggested change would be to capitalize "Smith" since it is a proper noun.