“So Gideon went.” Gideon went away, but the text does not say where. We do not know how far away he went, but that is likely why he made sure the stranger would stay and wait for him.
“a young goat.” A huge sacrifice for Gideon since meat was scarce.
“a young goat and unleavened bread.” This seems to make an allusion to Passover, with its unleavened bread and goat. But the unleavened bread may have been because Gideon was in a hurry.
“an ephah of flour.” This is almost 8 gallons (over 23 quarts; 22 liters). This is a huge amount of flour and shows the extreme sacrifice Gideon was willing to make to please God and win His favor.
“under the oak.” The angel was still sitting under the oak.