Printing a poster at the conference
Reimbursement is related to a particular institute's policy; and taking by plane - to a particular airline's policy, so I won't speak about it.


  Being unable to print the poster when you get to the conference.


Possible problems with printing facilities:


they may by further from the conference venue than expected (or not as easy to get to them, or masked so it's they are not easy to find even if you are nearby),
delays larger than you expect (at least assume "the next day", in general or due to other prints ordered),
page can be out-of-date, or they may be not working for some reason,
they may not print A0 format (permanently or temporarily),
local holidays (or local customs related to working hours) may be different.


(I printed posters on-site two times, and it went almost without problems; some of people I knew had problems, especially with instant printing and poster sizes).