In the 79th episode of STTNG, a character mentioned that the Enterprise had passed the planet Camus II, which had been featured in Turnabout Intruder - the 79th episode of the original series.
A broken sign reads "King Mei Hotel", which was a hotel in 'Another 48 hours' - the sequel to a move where Denise Crosby (who played Ishara Yar's sister) had one of her first film appearances,