In terms of automatic entitlement, all you get is refrehsments/food voucher and telephone card.
In addition to that, under the Regulation implementing the Montreal Convention in EU law, carriers are liable for damages resulting from delays up to SDR 4150 (roughtly €4800). However, here, the compensation is not automatic. You need to bring a claim with KLM, identifying the damage you have suffered, suported by evidence (eg: copies of invoice), that can be attributed to the delay. The liability of the carrier in case of delays is presumed but they can exonerate themselves by establishing that they took all reasonable measures to avoid the damage of that it was impossible for them to take such measures.
As to whether your taxi costs can be regarded as a damage resulting from the delay of the plane, this is essentially a matter for Dutch law. I don't know anything about Dutch law but it could be tricky in so far as trains were still running, even though you would have had to wait 50 mins.