The other day I was reading a review of Shrek 2 in the paper, and the author referred to both Shreks as "anachronistic".

Can something that doesn't occur in a "time" be "anachronistic"? It is a fairy tale, which is timeless--as in, not something that has a time and date for the setting. So it can't be anachronistic, because something that has no time can't have things that are from the wrong time, right?

While I haven't seen either the movies, nor that particular review, two possibilities come to mind.
The reviewer could be speaking of the style and/or content of the movie itself. The acting styles of many movies in the early 1930s looks very stilted today. It is not that every actor then was a lousy actor, it is that the style of acting in many movies then was so different than the style today. The stylistic content of many movies then is also different. Today, we would laugh at the idea that wealthy men in the US wake in the morning and put on a dinner jacket or a tux before eating breakfast, yet many of the movies showed exactly that. Fritz Lang's classic "M" showed the criminals of a German city holding meetings, with various representatives of the "unions" there, deciding on a course of action. ( "You, you have the pickpockets follow him. You there, get your beggars in line.") Of course, all the criminals were gentlemen and ladies, and conducted themselves civilly in a trial that they held. Would we accept that in a movie today?
While a specific time may not be mentioned in a movie, a movie sets its own place in time. A movie in which everything seems to indicate a time period prior to the widespread use of electricity yet shows someone using a radio would make no sense. The radio is an anachronism in such a setting. The same is true for a knight on horseback, in full armor, removing his gauntlet to look at his wristwatch. Viewers will accept almost any setting in a movie, but, unless we are shown that this is a time/place where much of what we know doesn't apply, we expect certain rules to apply: cavemen didn't squeeze a plastic bottle to put catsup on their meat, and knights didn't use WD 40 to make their armor move better.
Then again, the reviewer could be talking about something else entirely.

In these movies, the overall setting is kind of middle-ages-esque, but not in a particular time. Mostly the "products" shown are like non-middle-aged things made to fit the movie (for example, in Shrek 2 there is a Fairy God Mother who runs a massive factory producing potions and spells for the mass market, and she advertises through business cards that poof into a hologram of her obviously making a recording..."Are we on? Are we on?")

I thought perhaps the reviewer was refering to the middle ages, but since it is so clearly a fairy tale I was confused. Thank you for your help David