There are 13 Trophies that can be collected.

BRONZE

Hook-a-donut
Skewer the donut in 'The Fairground'

Speed king
Win an online match in under 5-seconds

Jaywalker
Make it through 'The Highway Code' without being hit by any cars

On-call
Take the doctor's car back to work

Cake pacifist
Save the cake

Antique Collector
Save the priceless antique

Paradox
Catch something you threw

Vertigo
Complete 'Up on the Roof' without falling off

Striiiiike!
Go bowling with Vikings

SILVER

Viking Impaler
Knockout 25,000 Vikings in quest mode

Online Champ!
Win 50 public online Vs matches or Gold Rush tournaments

Persistence
Earn a gold star in all solo challenges

GOLD

100% complete
Complete all quest levels, unlock all characters and earn all other trophies

http://www.ps3trophies.org/game/when-vikings-attack/trophies/