DON "HI HO" SILVER:
"Well, as Perry Mason used to say..."
"See you in court."
'The Rockford Files'
"The Attractve Nuisance"
This is pretty easy to splain away. Don Silver, a seedy ambulance chaser, wasn't making any references to Perry Mason, the television character. The televersion of Mason was famous, getting his picture in newspapers and on the news for years. It would be easy to assume Silver was quoting the real lawyer.
As for Silver using the past tense ("used to say"), Mason by this point in time (early 1978), Mason had already accepted the judgeship in Colorado and so moved away from L.A.