|Note: If you find an official source (i.e. an interview, correction or note in a later edition by Spider Robinson himself) explaining any apparent contradictions, please add another paragraph with the explanation, don't change the information already present. If you happen across another contradiction, categorize it properly|
Jake's First Wife
During "Fivesight" in Time Travelers Strictly Cash Mike Callahan observes that Jake claimed his wife's name was Diane, not Barbara as established in the other books.
At the end of Callahan's Secret Jake laments that Lady MacBeth had been in the bar when it was nuked. Later on in the series, he's shown playing Lady MacBeth again. It's possible that Jake got another guitar and also named it Lady MacBeth, but that seems unlikely.
Mary's Place & The Place
The end of Mary's Place takes place in the fall of 1988 (Callahan's Legacy, Chapter 1). The gang arrives in Key West in March 1989 (Callahan's Key, Epilogue "It was a hot Friday evening in March of 1990--the first anniversary of our arrival in Key West!"). The launch date of STS-28 also confirms the 1989 setting of Callahan's Key.
- Discovery, she was. Flight STS-29, the twenty-eighth Shuttle mission. (STS-28, Columbia, had developed sderious problems, we were told, and would not lift until the following August.) (Page 131 of the Bantam Library Edition, 2000)
Erin is mentioned as 14 months old a short while before the gang moves to Key West (Callahan's Key, Chapter 1 " 'Sure, Uncle Nikky,' my fourteen-month-old said, releasing his fingers.") and 15 months old the day they arrive (Callahan's Key, Chapter 10 "'I'm fifteen months old,' she told him, 'and I'm kind of a genius.'").
So counting forward from her birth in Fall 1988 in Callahan's Legacy would make Erin 15 months old in early 1990, but Callahan's Key is set in 1989 when Erin should have been less than a year old. And Erin couldn't have translated elsewhen to age as Jake himself says that Mary's Place was closed over a year at the beginning of Callahan's Key.
Unfortunately both books make reference to real-world events, making the reconciliation impossible. Solace's death coincides with the Morris Worm on November 2nd, 1988, establishing the timeframe of Callahan's Legacy. The launch of STS-28 occured on August 8th, 1989, establishing the timeframe of Callahan's Key.
Transiting and Translating
Erin & Mixed Loads
Mary Callahan-Finn explains Translating and Transiting to the gang after she and Finn arrive at Mary's Place. She explains that Translating is used for space and time travel and organic and inorganic loads can't travel together. She also explains that Transiting can be used to move only through space in an infinitesimal amount of time and can take organic and inorganic in the same load. There was no problem Transiting with the metal making up Mickey Finn's cyborg components.(Callahan's Legacy, Chapter 6)
In Callahan's Con When Little Nuts puts handcuffs on Erin's ankles. Jake, Zoey, and Willard all reacts as if Erin was trapped by this even though they were all present when Mary explains Transiting and Translating. Jake claims that you can teleport in or out of clothing but not if metal is touching your skin. (Since Finn can Transit but not Translate because he has metal parts then this can not be true.) Erin should be able to Translate (or Transit) right out of them the same way she leaves her clothing behind on numerous occasions. During the events of Callahan's Key Erin Transited on multiple occasions (although she never took mixed loads).
Starting at the end of Callahan's Key (when Mike, Sally, Mary, and Finn all show up naked at The Place; indicating they had travelled through time, even though that is impossible for a cyborg) and straight through Callahan's Con, Spider seems to have changed the rules.
Lady Sally, Mixed Loads & Method
In Callahan's Lady Lady Sally McGee translated with Maureen to Harmony in order to replicate a counterfeit $10 bill. In this instance she and Maureen walked through a "membrane" camouflaged as a wall and emerged on Harmony in the Callahan's native timeframe. They translated clothed and Lady Sally carried the $10 bill and tweezers through. Mike Callahan also joins them apparently in his Callahan's Place garb.