Police etc:
There is a strong tradition that emergency services won't enter an area that the police deems 'unsecure', which means demos peaceful or otherwise and the like. The police employ a rapid deployment tactic which often sees people getting hit by speeding riot vans. Also batons and pepperspray are often employed and tear gas as well as dogs are not uncommon riot control measures. Recently police have been issued with two water cannons with which we have no experience as of yet. Less lethal ammunition such as 'baton rounds' and 'rubber' bullets is not used. Police horses in Denmark are not combat trained as in other countries and so are not used in confrontations. It should also be noted that all police in Denmark carry firearms.
Weather:
Usual temperatures for December arey around freezing, often slightly below. Also typically it rains rather heavily in this period and the wind is usually strong. Hence hypothermia is a real and serious concern for many protesters staying outside for extended periods of time. Bring warm clothes, spare clothes and water proofs if possible.
A&E / ER services:
There are five A&Es in the immediate area of the city. Treatment at these is free (EU citizens are asked to produce their blue health insurance cards but treatment is very rarely withheld regardless). Staff at A&Es are not allowed to contact police regarding patients unless gunshot wounds are involved, but this is not a complete guarantee. Likewise police are not allowed to enter hospitals to search for suspects, but have been known to maintain a 'vigil' outside nonetheless.
Other:
No wild animals worth mentioning.