Apollo XI mission carried a plaque to the Moon featuring a map of the Earth. So do the Pioneers with a plaque with symbolic indications that may help to find its origin.
So, here comes the question: Did the Huygens probe carry any hint that may be helpful to find the Earth? If not, why?
This question may extend to any spacecraft that is expected to survive a landing in other places than Earth, like Mars rovers, or spacecraft whose final location is not a known one, e.g. New Horizons.
No plaques are needed to identify the origins of any of our deep space probes, landers, rovers and so forth. Any civilisation technologically at least as advanced as we are from the 20th century onward shouldn't have problems identifying that they could only have came from the Earth. In fact, I would dare go as far to claim you'd only really require a small part of one probe, perhaps an electrolytic or a ceramic capacitor, to infer that the only place where it could have been manufactured was on the Earth, and you could likely establish also sufficiently precisely when, by the level of decay of its materials or even carbon dating them.
A whole spacecraft would hold other clues, such as the strength / resolution of its communications subsystem and where its antennae are pointing, limiting possible source within our Solar system or closer, and give you a hint of where to look for other technosignatures. Some of the materials used by it could only have been synthesized and they don't exist naturally anywhere in our neighborhood. Any industry producing them would leave behind markers, such as, say, atmospheric pollutants that could be detected from another celestial in our Solar system, perhaps by astronomical spectroscopy.
So even with a few clues, technologically advanced civilisation could establish when they were manufactured, when they were last used even (exposure to the environment of different parts could give a clue about that), what direction in the skies they were communicating with and a good approximation of at most how far away they were from where their signals were supposed to be picked up. They could then investigate possible candidate celestials and establish that the Earth is the only one that contains traces of industrial pollutants needed for fabrication of some of the probe's materials in its upper atmosphere and that they must be there from around the time when the probe was built. As soon as they'd realize no other celestials in our vicinity match all these requirements, they would've solved the problem of establishing some probe's origins. Simple really.
Plaques and alike would likely be meaningless to anyone not understanding our languages or having required equipment to play records, analogue or digital. If analogy is required, just think of all the data carriers from as little as a few decades ago that we don't even have any readers for anymore. Remember floppy disks? Punched cards? Do you still keep around all the required hardware to read them? Probably not, and even if you did, they might not be working any more, and/or you wouldn't be able to make sense of the data they hold. And even the launching programs don't for some of the spacecraft that are still functional, like e.g. NASA misplacing communications equipment needed to control the ICE/ISEE-3, that is now a crowdfunding effort to redirect it to its original orbit and do science again by means of software-defined radio equipment.
So those plaques, gold records, DVDs (like on the Cassini spacecraft), and whatnot that we're attaching to our probes and landers are really more for ourselves than any yet unknown civilisation (distant future us, or anyone else). And they're a subject to decay, so they won't last or be readable for eternity anyway.
