When Cal and Jack step out of the storage of the toy store in Germany, both doorknob and light switch are clearly American. Also, cemeteries are laid out differently in Germany like the one seen in the following scene.
Cal and Nick leave a mall in Philadelphia, PA and travel to a Air Force Base to depart. However, the Fighter Jets have "TY" Written on their tails, which stand for Tyndall Air Force Base, which is just east of Panama City Beach Florida. This is the F-22 Training Squadron based at Tyndall AFB.
The Netherlands is incorrectly named Holland when the simulations are done for Belgium and Holland (The Netherlands).
When delivering presents in the final moments of the film, Santa is shown moving across the globe from West to East (US ' Brazil ' Paris ' Sydney). But due to timezones, children in Sydney wake up to Christmas a full day before children in the US, so Santa should be moving the opposite direction.
Hiding in the tunnels beneath the original workshop and using the multiplicator that was there was obviously part of Gryla's plan. If she knew about these aspects of the North Pole base, it does not make sense that she did not know the location and needed Nick to hack into the seismography network to find it.