Submitted by everythings-shiny-captain, who says:

I live in Calgary, so I’m familiar with Calgary Transit’s “Route Ahead” plan to expand light rail and bus rapid transit services. Out of curiosity I searched for Edmonton Transit’s plan and found this terrible map of their light rail development plan. What is going on?!

Transit Maps says:

At first I thought this was just yet another poorly drawn, generic “future corridors” map and was wondering what the fuss was about… and then I looked at the PDF on my iPhone (second image above). 

Whoops! Suddenly, I could see all the working layers from the original Illustrator file as well. Even though those layers were turned off before the export to PDF, they are still visible when viewed on some mobile devices (the layer settings in the PDF aren’t being honoured by the PDF renderer on the device).

The lesson here: always clean up/flatten your artwork before output, and test how it looks on as many devices as you can!

Source: City of Edmonton website (link no longer active)