"Sidon most certainly does appear to be out of the way if Jesus were going directly back northwest shore of the Sea of Galilee from which he had come. But Mark 7:31 indicates that he looped around and approached the southeast shore of the Sea of Galilee through the region called Decapolis. If you view the Sea of Galilee as a clock, Decapolis (Greek for "ten cities") was a region which bordered the sea from 3:00 to about 6:00.
Orthodox Jews did not normally travel in this area because the region was almost entirely inhabited by Gentiles and Hellenized Jews. Jesus, however, brought his disciples here immediately after their time in the regions of Tyre and Sidon. Now, an important question: What did these two regions have in common?
What they had in common was lots of Gentiles. Since Jesus is reported to have spent most of his ministry in Jewish territory, it is significant that these areas should be linked together. What Matthew and Mark are probably saying is that Jesus took his disciples on one last ministry tour through the Gentile regions. This mission would set a precedent for the disciples’ later concern regarding being His witnesses ‘even to the remotest part of them earth,’ even among the Gentiles. Beginning on the northwest shore of the Sea of Galilee, they would have traveled northwest to Tyre, northeast to Sidon, southeast to the region of Decapolis, and west to the Sea of Galilee. Far from showing ‘a lamentable ignorance’ of the geography of Palestine,
the passage helps explain why Jesus did not go directly back to the northwest shore of the Sea of Galilee, the location identified as his home.
Wilson’ further contention that there was no road from Sidon to the Sea of Galilee is likewise immaterial. The gospels report numerous occasions where Jesus was going up mountains or into the wilderness to pray, and he consistently conducted his ministry in rural areas. There is therefore no reason why Jesus and the disciples could not have walked the less than twenty miles from Sidon to the Valley of Lebanon. Their route along with the south side of Mount Lebanon would not have been too difficult. Only further north are the mountains of Lebanon imposing. This route would have allowed Jesus and is disciples a more direct path around to the southeast side of Galilee." (Josh McDowell & Bill Wilson,
He Walked Among Us Evidence For the Historical Jesus [Thomas Nelson Publishers, Nashville TN 1993], pp. 209-210; bold emphasis ours)"
Responses to Bismikaallahuma : Geographical Errors Within The New Testament [Part 2]
So, no contradiction.