I think a lot of people when they respond are just focusing on the geography facts the authors got right, but there is also some
analyzation of those facts that are important too. For example here is some analyzation of the things Gospel writer John got right.
From the same cited link above:
2. Given the early Christian tendency towards asceticism, the wine miracle is an unlikely invention (2:8).
8. Jesus' own testimony being invalid without the Father is an unlikely Christian invention (5:31); a later redactor would be eager to highlight Jesus= divinity and would probably make his witness self-authenticating.
11.Christ's command to eat his flesh and drink his blood would not be made up (6:53).
12. The rejection of Jesus by many of his disciples is also an unlikely invention (6:66).
13. The two predominant opinions of Jesus, one that Jesus was a Agood man@ and the other that he Adeceives people,@ would not be the two choices John would have made up (7:12); a later Christian writer would have probably inserted the opinion that Jesus was God.
14. The charge of Jesus being demon-possessed is an unlikely invention (7:20).
16. Jewish believers wanting to stone Jesus is an unlikely invention (8:31, 59).
18. Expulsion from the synagogue by the Pharisees was a legitimate fear of the Jews; notice that the healed man professes his faith in Jesus only after he is expelled from the synagogue by the Pharisees (9:13-39), at which point he has nothing to lose. This rings of authenticity.
19. The healed man calling Jesus a Aprophet@ rather than anything more lofty suggests the incident is unembellished history (9:17).
22. Given the later animosity between Christians and Jews, the positive depiction of Jews comforting Martha and Mary is an unlikely invention (11:19).
23. The burial wrappings of Lazarus were common for first-_century Jewish burials (11:44); it is unlikely that a fiction writer would have included this theologically irrelevant detail.
28. Anointing of a guest=s feet with perfume or oil was sometimes performed for special guests in the Jewish culture (12:3); Mary=s wiping of Jesus= feet with her hair is an unlikely invention (it easily could have been perceived as a sexual advance).
30. Foot washing in first-century Palestine was necessary because of dust and open footwear; Jesus performing this menial task is an unlikely invention (it was a task not even Jewish slaves were required to do) (13:4); Peter=s insistence that he get a complete bath also fits with his impulsive personality (there=s certainly no purpose for inventing this request).
31. Peter asks John to ask Jesus a question (13:24); there=s no reason to insert this detail if this is fiction; Peter could have asked Jesus himself.
32. "The Father is greater than I" is an unlikely invention (14:28), especially if John wanted to make up the deity of Christ (as the critics claim he did).
36. Jesus' admission that he has gotten his words from the Father (17:7-8) would not be included if John were inventing the idea that Christ was God.
38. The name of the high priest=s servant (Malchus), who had his ear cut off, is an unlikely invention (18:10).
42. Identification of a relative of Malchus (the high priest's servant who had his ear cut off) is a detail that John would not have made up (18:26); it has no theological significance and could only hurt John's credibility if he were trying to pass off fiction as the truth.
54. Mary mistaking Jesus for the gardener (20:15) is not a detail that a later writer would have made up (especially a writer seeking to exalt Jesus).
58. The fear of the disciples to ask Jesus who he was (21:12) is an unlikely concoction; it demonstrates natural human amazement at the risen Jesus and perhaps the fact that there was something different about the resurrection body.
http://www.theologyweb.com/campus/showthread.php?t=51643
Notice all the times the term unlikely invention is used in the examples above.
