In the 1980 film Dangerous Davies, Mod Lewis was Welsh rather than Irish.
They had to have used at least three different dogs for for the role of Dangerous' St. Bernard. The first one is all dark, the second one had a dark head/face with a mostly white body, the third one looks like a typical brown and white St. Bernard. The breed used in this series was a Landseer Newfoundland, not a St. Bernard. They definitely used multiple dogs with decidedly different markings.
The dog's name isn't given despite being a regular character. In the 1980 film Dangerous Davies, the dog isn't a St. Bernard but is still a large dog named Kitty.
In the 1980 film Dangerous Davies, Mrs Davies was named Doris rather than Julie.
Watching the Pilot episode: Bar scene shows a girl in a red dress going to the jukebox. Next bar scene, the girl appears in the same red dress, she slips and you hear a yell. Next bar scene, the girl is on a stool, again in the background, and you see a garter around something white and as the scene progresses you see that the girl has a cast on her leg with the cast resting on a second chair. Of course the missing girl was wearing a red dress but not exactly the same.