For the most part the pilot didn't differ all that much with the series. Instead of the format of the series where there would be a preview of scenes from the show followed by the title sequence starting Harry calling Harrison for a lift - the pilot had a short teaser in which the show's plot begain, cutting to the shot of Harry that normally came after saying "What could possibly happen"? Also the fox drawing is missing from the final end credits.
A slight goof with time in this episode...When Harry is getting ready for the funeral he mentions that the dinner party was 'the other day'. Yet later when the next door couple come to see Harrison and Cindy they thank them for the party they threw last night. Seems more likely that Harry's line is the accurate one, since its unlikely that the dog could be poisoned, autopsy conducted and a funeral arranged and conducted all in one night/morning.