CAN-Bus shield, SD-card module & LED_BUILTIN use D13; possible collision?
Yes you are in danger of a collision, how much danger I can't say, but the potential is there.


You could stop using the LED on D13?
Could you move the pins of your SD card reader, or get a different one that allows I2C or SPI interfacing?


I guess there is nothing that can be done to the CAN bus device, but if there is it might be a good idea to move its pins.