There is a scene where Tench is sitting at a table drinking whiskey. Whilst the label is pointing away from the camera, it is possible to tell from the embossing on the side of the glass bottle that it is a bottle of Bushmills Irish whiskey. This specific 'embossed' bottle type was first introduced to market in 2010. And was certainly not around in the 70's when this show is set.
In at least two episodes, there's a poster on Debbie's wall over the table advertising a concert by garage punk band The Cynics. This band was formed in 1983, so they couldn't be playing in the late 70's when season 1 is set. And it couldn't be another band with the same name, since the logo and locale (the advertised concert is in Pittsburgh, the aforementioned band's home town) fit.