Suppose some scholar or pseudo-scholar announced that he had found an ancient manuscript containing a lost chapter of the Gallic Wars: that would be thrilling, at least for us pedants. But suppose the new chapter contained a sentence in which Caesar mentions drinking an orange soda in a tall glass with ice cubes while preparing his battle plans. Scholars would reject the soda as a blatant anachronism proving the passage a modern forgery.

Or perhaps some would not. There is nothing physically impossible in the idea that Caesar could drink an orange soda. It could theoretically have happened:

1. In conquering Gaul, Caesar may well have visited the mineral springs of Perrier, where the water is naturally carbonated -- in effect, club soda bubbling up from the ground. While there, he may well have drunk some of the local specialty.
2. Oranges might theoretically have been imported from China in Caesar's time, since we know that there was trade between China and Rome. The fact that oranges are not attested in Rome until much later (mid-4th century, according to this site) does not absolutely prove that a very few were not imported earlier. And if they were imported, it might have occurred to someone to squeeze some of the juice into a container full of Perrier water, perhaps with some honey to sweeten it. (Otherwise, it would more flavored seltzer than orange soda.)
3. Glass vessels were far less common in Caesar's time than they would be a century or two later, after rapid advances in glass-making technology in the first century A.D., but it's conceivable that some local Gallic craftsman was ahead of the technological curve.
4. A century or more after Caesar's time, wealthy Romans and members of the imperial family did have ice from the Alps to cool their drinks in the summer. I don't have the reference, since my books are in storage, but apparently a large enough block of ice, covered with blankets, can be transported from the Alps to Rome even on a horsedrawn wagon before all of it melts away -- we know this because the Romans sometimes did so in later years. Though he was almost certainly too busy conquering Gaul to worry about such things, it's conceivable that a wealthy and powerful politician like Caesar could have arranged similar shipments of ice to his headquarters in Gaul, and had them chopped by hand into well-matched conveniently-sized cubes by a skilled local craftsman to cool his hypothetical drink.

Of course, each of the necessary ingredients for a glass of orange soda with ice cubes, though not technically impossible, is so extremely unlikely in Caesar's time that the combination of all four is about a trillion times less likely than a simple hoax. Any passage such as I have imagined could in fact be dismissed as a forgery composed by some modern too ignorant to avoid even the grossest anachronisms.

Do I need to spell out the moral as if I were Aesop telling animal fables to little children?