Not sure if this has been discussed before, but in "Ashes to Ashes", when Columbo is trying to figure out what the initials "SB" could mean, he asks Eric Prince (Patrick McGoohan) what he thinks. He says, "Sonny Bono, Sandra Bullock, Steven Bochco..."
As far as mentions in general, in Uneasy Lies The Crown, the conversation could have continued,
"You're Nancy Walker"
"Yes"
"From the Rock Hudson series, McMillan and Wife, and, you know, the Mystery Wheel, with Banacek and Columbo, and that cowboy, McCloud".
How could Sandra Bullock be mentioned and she wasn't even around then?
Ashes to Ashes first broadcast on October 8, 1998. Sandra Bullock had already done Demolition Man (1993), Speed (1994), A Time to Kill (1996), Speed 2 (1997) and Hope Floats (premiered May 29th 1998) before then.