“When evening came.
Jesus
And his disciples
Went out
Of the city.”
Καὶ ὅταν ὀψὲ ἐγένετο, ἐξεπορεύοντο ἔξω τῆς πόλεως.
This is a unique saying of Mark, but not inconsistent with the other gospel stories. When evening came (Καὶ ὅταν ὀψὲ ἐγένετο), Jesus and his disciples went out of the city (ἐξεπορεύοντο ἔξω τῆς πόλεως). Notice that they left Jerusalem at night, probably going to Bethany, which was not far away and where they felt safe.
Eugene Finnegan Bible Project 