There's a lot of conflicting information—including Erasure's own website discography—regarding the release of "Wonderland" in the United States. Erasure's site claims it was released on May 1st, 1986 in the US (which is probably why Wikipedia also suggests the same date). I've read comments by people claiming it came out as late as September! All of this conflicts with what I personally remember, which is having the cassette in my possession, and blaring at full volume on my modest stereo system, in the early Spring of 1986. In fact, I unearthed my own written evidence that I owned both the "Who Needs Love Like That" 12" and "Wonderland" cassette album prior to May, 1986!
Further complicating things, the back of the insert for the US "Wonderland" CD (first released by Sire Records in 1987) begins, "Released in February, 1986...". Even that seemed suspiciously early. So, I decided to do some research.
Using the searchable online Billboard and Cash Box magazine archives, I discovered the earliest mention of "Wonderland" is in Billboard, on page 26 of the February 8, 1986 issue; as part of the weekly "New Releases" section. This section simply lists artist name, album title, format(s) of the release, label, catalog number, and suggested retail price:
ERASURE
Wonderland
LP Sire 1-25354 / WEA / $8.98
CA 4-25354 / $8.98
In my examination of this weekly section of Billboard, it's clear that sometimes a "New Releases" listing might come just a few days after an album's verified release date, and sometimes it was published up to a month after a verified release date. These announcements—as far as I have been able to determine—never pre-dated an album's actual release date.
The next mention of "Wonderland" is an album review found on page 12 of the March 15, 1986 issue of Cash Box magazine. Billboard published their review of the album one week later, on page 78 of their March 22, 1986 issue. These reviews were usually written and submitted to editors, at the latest, 1 week PRIOR to actual publication dates. Which means the Cash Box review had to have been written before March 8, which suggests the album was commercially released prior to that date.
While "Wonderland" did not chart on the Billboard "Top Pop Albums" chart, it DID chart on the Cash Box "Top Albums 101/200" chart! In fact, it charted for 11 weeks! It debuted at #173 on March 29, 1986 (page 21) and peaked at #163 on April 12, 1986 (page 25). That's a significant disparity, for an album not to chart at all on Billboard, while it charts as high as #163 on Cash Box! But, at the very least, this is actual evidence the album was being bought and sold in mid-March in enough numbers to warrant a chart position (Cash Box's chart was based solely on actual units sold by their panel of retail reporters).
So, it turns out the "Released in February 1986..." statement on the Sire "Wonderland" insert is, in fact, accurate! Very odd for a UK-based band's debut album to be released in the US 4-months BEFORE its UK release date of June 2, 1986!
Mystery solved!
Now then, what about the secondary mystery of why the US release of "Wonderland" features an entirely different mix of "Oh L'Amour" than the eventual UK album? I think it's reasonable to assume, since the US released the album 4 months before the UK, that this was likely the original album version of the song, and Mute opted to further remix it for the eventual UK single release in April and then the UK album version released in June. This US album mix, along with the PWL Funky Sisters 12" and US 7" remixes, remain my favorite versions of the song to date.
As a P.S., I'll just add one more related tidbit: The Sire CD release of "Wonderland" was announced in Billboard's "New Releases" section on May 9, 1987 (page 53). Important to remember that, at the time, the CD was still a relatively new format that was just beginning to work its way into the collections of the music-buying public. 1987 was the year Warner (WEA) began to aggressively re-issue older "catalog" albums in the US to benefit from the new CD format. In fact, few newly released albums in the mid 80's were available—upon release—on Compact Disc. Usually, the only options were LP and cassette; CD versions generally arrived several weeks, or even months, later.
The first Erasure release I was able to buy on CD from day one was the "Crackers International" EP which was released in the USA on April 25, 1989. The first Depeche Mode album I was able to purchase on CD from day one was "101", released on March 14, 1989.

