I recently read 'The Snail and the Ginger Beer: The Singular Case of Donoghue v Stevenson', an excellent book about 'that snail case' by barrister Matthew Chapman QC, ("a killer advocate with great command of the law.” Let's hope that testimonial was not meant literally) and learned some interesting things about the most famous common law case of all time, Donoghue v Stevenson  AC 1 (**click to read the actual case. You know you want to**)
Guess what? SPOILER ALERT: There Probably WAS A Snail in the Bottle
Mrs Donoghue's claim that a decomposed snail had plopped out of the ginger beer her friend had bought for her, causing her illness and shock, was never actually tested in court, of course; the issue that was the subject of the litigation was whether she had a cause of action. But, it doesn't seem all that hard to believe that a snail did find its way into the bottle of ginger beer and remained undetected, before being turfed out of its fizzy grave into a bowl of ice cream.
Exhibit A: If you want to get rid of snails in your garden, you leave a 'beer trap' out for them. Snails love beer and just can't get enough of that sweet, sweet, yeasty taste. And ginger beer, made from water, sugar, yeast and (wait for it) ginger, is also sweet, sweet and yeasty. In Mrs Donoghue's pleadings, she stated that Mr Stevenson's methods were defective and that 'ginger beer bottles were washed and allowed to stand it places to which it was obvious that snails had freedom of access from outside the defendant's premises'. Mr Stevenson responded 'no bottle of ginger beer ever passed out therefrom containing a snail'. Which isn't really answering the question now, is it, Mr Stevenson?
Exhibit B: It appears that snails weren't the only creatures that had been finding their way into ginger beer bottles in the west of Scotland in the years prior to Donoghue v Stevenson. There had been two cases in the late 1920's involving dead mice in ginger beer bottles and one had even been successful at first instance (the case, that is, not the mouse. The mouse was dead, remember.). Both cases were appealed and heard together. Interestingly, it was accepted by the court that the mice were in the bottles even though, ultimately, it could not be inferred that this was as a result of the negligence of the manufacturer. If a mouse can get into a bottle of ginger beer it's not that much of a stretch to think that a snail could get in there as well. (Even if it took the snail a LOT longer, amirite??)
Exhibit C: Ginger beer bottles in the 1930s were seriously opaque. As in 'not even a little bit transparent'. As in 'no speck of light was getting through those bad boys'. Although times had moved on from earlier days when stoneware bottles were used, the glass bottles produced in the 1930s were still totally un-see-through-able (I'm sure that's a word). A snail who did not wish to be seen would be more than capable of evading detection in a Stevenson's ginger beer bottle.
So, there you have it. One of the greatest mysteries of our time solved. Looks like we didn't need the facts to be established in court after all. You're welcome, common law.
* It probably won't. I just put that in the title because the Internet led me to believe you'd be more likely to read this article. I'm sorry. I feel really bad you fell for this.