In the episode where Ray & Paulie receive their passports it state that Ray was born in 1947 that mean he would have been only 16 when he first runs into Torello and he is already married with children.
During the Season 1 episodes (near the end of the season) where Manny Weissborn and the other mob bosses are meeting at a country club and arguing over whether or not to get involved in the drug trade or the takeover of Las Vegas, pay close attention to the large plate glass windows. During the night-time scenes, especially when Weissborn goes into a rant, you can see the reflections of stage hands holding boom mics, running cameras, and holding up cue cards for the elderly Joseph Wiseman to read.
The goof item below may give away important plot points.
The first season takes place from 1963 to 1964 and ends with the supposed death of Ray Luca and Paulie Taglia. When the second season begins, it picks up where the previous season left off (Presumably within days after Luca and Taglia's death since their funeral takes place in the first episode of the second season). However, throughout the course of the second season, there are references made to the fact that the time period is 1965-1966. Which means there is a one year gap in the time line.