Never make things too easy. Especially with maps.

A map might purport to show the heroes exactly where they need to go to get what they want. But it'd be boring if there were no complications along the way. Herewith, some complications!

• A map can be incomplete, in that it doesn't indicate dangerous regions or obstacles along the way.
• The map might imply a best/fastest route, which for some unindicated reason is in fact not the best/fastest route.
• A map might be incomplete in that it only indicates the way to the goal from a certain starting point - but it's not clear where that starting point is.
• The map could be deliberately misleading or false. It may indicate treasure where there is in fact danger.
• The map may not conform to any known region that the heroes know of, or can easily find out about.
• The map be be abstracted so that it doesn't match normal map-making conventions, utilising odd symbols.
• The map may not indicate all paths/roads, so that when the map reader comes to an intersection, they are unsure if it's indicated on the map or not.
• The scale of the map may be very loose, showing only rough positional relations, but not giving any indication of distances.
• The "north pointer" on the map may point in a different direction, without any clear indication.
• Distance units marked carefully on the map may be in obscure or unknown units.
• The map may be for a different reality or plane of existence - for example a map of the Dreamlands, or the Astral Plane.
• For large enough regions on a spherical planet, the map projection may distort shapes and distances in misleading ways.
• The map may be out of date. New roads and even cities may have appeared since it was drawn up.
• The map colours may be unconventional: e.g. green for water, blue for land.
• The legend can be written in an unknown or arcane language. This is good if warnings are actually included on the map.
• Smudges, fading, or burn marks obscuring critical areas of the map.
• The map is one of those "it's not the actual treasure map until you fold parts of it over" kind of maps.
• The map has crucial information written in invisible ink.
• You have to look at the map through a particular warping crystal or arrangement of mirrors to see it correctly.
• The map is delicate and crumbles to dust after the heroes have a quick glance. (You can simulate this by showing the players a map and then taking it away after a short time, then have them sketch what they think they saw and plan their travels using that.)
• Areas may be marked as "terra incognita" - the mapmaker had no idea what was there.
• Places have changed their names since the map was made. Perhaps nobody even remembers the old names written on the map.
• The map connects places in a topologically correct manner, but laid out oddly, with lots of crossing paths that don't really intersect.
• The map is intelligent and able to change its display. It either enjoys practical jokes or is outright malevolent. Perhaps until the heroes satisfy some of its goals. (Think the Marauders' Map from Harry Potter, but solemnly sworn to be up to no good.)
• The map is incapable of showing the details of some crucial 3-dimensional structure (e.g. a maze), due to being drawn on 2-dimensional paper.
• The map is tattooed onto some person, or animal, that isn't necessarily okay with you wanting to keep checking the map.
• The classic map in several pieces, which need to be tracked down to assemble the full map.
• The map is a magical/technological spy device, tracking the position of the users and sending the information back to... someone.
• The map is valid, but is a representation of senses not possessed or commonly used by the reader. For example, a transcription of scent-lines or air currents.
• The map is not a small scale representation of a large area - it is an enlarged representation of a tiny/microscopic area.
• The map is not drawn on paper, but is a sculptural representation.
• The map is a sliding puzzle with geomorphic pieces, and some other clues are needed to determine the correct arrangement. The desired destination may be on the missing piece.
• The true map is formed only when multiple maps are overlaid, or combined with some logical function such as the XOR operator.
• The map is 4-dimensional. (We're not even sure what this would mean, but it sounds cool.)
• The map contains a timeline component, indicating certain things in the past. And possibly also in the future...
• The map has been extended by a fanciful author beyond the actual Edge of the World. If you follow the map without due care, you could fall off the world.
• The map wraps around neatly at the edges. Why would it do that?
• The map wraps around neatly at the edges... if you flip one edge upside down.
• It's a map of what was planned to be built, but never eventuated.
• It turns out it's a map to someone's heart.
• The map is from a parallel dimension, so the landmarks carry over but the treasure/goal isn't there.
• Following the map allows you to cross over into an alternate reality, but without the map to guide you, there is no way to find the crossover point.
• The map is actually a map to another similar-looking region, not the one the heroes think it is. For example, it's really a map to a Las Vegas Casino, not an actual pyramid.
• The map predates the Great Sundering/Rain of Fire/Ragnarok/other apocalyptic and world-reshaping event.
• The map doesn't indicate that an important region is on the back of a giant monster.
• The true treasure that the map leads to turns out to be the fun and comradeship you had along the way.
• The map is based on shadows and only shows things correctly when the sun is in a specific location in the sky on exactly one day of the year.
• Following the route marked on the map is actually part of an eldritch summoning ritual. Whoever completes the whole journey goes insane.
• And finally, the good old cursed map. Whoever reads it suffers a terrible fate.

Transcript

Finn: All right. We’ve got a map. Let’s go!
GM: Not so fast...
GM: Corey, a note.
BB-8: Oh, man! I’m checking Galactic nav charts and I can’t find anything that matches the region shown in this map.
Finn: That can’t be.
BB-8: It’s reading right, man!
Rey: Well, you’re not reading it right.
BB-8: It’s a trivial pattern match.
Rey: It is?
Yanni: Yeah, a straightforward affine-invariant cross-correlation should pull it out instantly, even if the map is warped or the scale is wrong.
GM: Right. What Jim said.
Rey: One of these days he’s going to contradict you. Then what’ll you do?
GM: Invent a desert planet off the top of my head and roll up a throwaway NPC who goes on to subjugate the Galaxy?
Yanni: Awesome!