In That 70s Show (1998-2006), the Pinciottis lived next door to the Formans. In That 90s Show, Gwen and Nate and their mother live in the house where the Pinciottis used to live. The kitchen looks different.
Several trailers for season 2 feature the song, "My Own Worst Enemy", by Lit. The song was released in 1999, but season 2 is set in 1996.
Like with many TV series that are set in the past, several pop culture things (or items) get seen or mentioned that weren't yet around in the year setting.
Eric Forman was 16 in 1976 when That' 70's Show (1998) started but Donna said he's 38. Which makes no sense. If Eric was born in March 1960. He would be 35 in 1995. It also doesn't make sense that Eric and Donna have a 14 year old daughter who later turned 15 in July of 1995. Because Donna wasn't pregnant when That' 70s Show ended. Also, there's no way Jackie Burkhart would be Jay Kelso's mother, because she was dating Fez when That' 70s Show ended. Although she might be Jay's stepmom. And somehow Donna got it right when she told Leia that she dated Jay's uncle Casey Kelso when she only found out about Jay minutes before and had no idea Michael Kelso would be his father.