As I'm sure you've discovered, the liquid in the bottle is only part of what makes fake booze believable. Like so much of what we do, the packaging is what sells the prop. The label, the bottle, the cap, the opener, all of these things clue us in to what we're looking at. Often, the brewery or distillery (now, more often, the corporation) will have product history on their website. If you are willing to dig deeper, some companies have historians that you can contact for information. Here are some links that I've come across doing label research. These sites have lots of items available for purchase, and they also can be excellent resources for research. I hope you enjoy them, and please feel free to add your favorite links in the comments.
This is a collectors' website with an extensive collection of all things beer. From cans to bottles to ads to matchbooks to caps, this website has almost 40,000 items. An excellent resource for the propster or breweriana collector.
Another extensive collection of beer cans, etc.
US Beer Labels
Pretty self explanatory, a large collection of American beer labels
Lots of photos of bottled beer from around the world.
Hundreds of wine bottles and labels.
Wine bottle and label photos.
Lots of labels, including some liquor labels.
Guess what they have? Antique bottles! Cooooool.